399636 has 36 divisors (see below), whose sum is σ = 1071252. Its totient is φ = 125184.

The previous prime is 399617. The next prime is 399643. The reversal of 399636 is 636993.

It can be written as a sum of positive squares in 2 ways, for example, as 202500 + 197136 = 450^2 + 444^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 399636.

It is a congruent number.

It is an unprimeable number.

399636 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 286 + ... + 938.

It is an arithmetic number, because the mean of its divisors is an integer number (29757).

2³⁹⁹⁶³⁶ is an apocalyptic number.

399636 is a gapful number since it is divisible by the number (36) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 399636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (535626).

399636 is an abundant number, since it is smaller than the sum of its proper divisors (671616).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399636 is a wasteful number, since it uses less digits than its factorization.

399636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680 (or 675 counting only the distinct ones).

The product of its digits is 26244, while the sum is 36.

The square root of 399636 is about 632.1676992697. The cubic root of 399636 is about 73.6582733988.

It can be divided in two parts, 39963 and 6, that multiplied together give a triangular number (239778 = T₆₉₂).

The spelling of 399636 in words is "three hundred ninety-nine thousand, six hundred thirty-six".