398649966 has 128 divisors (see below), whose sum is σ = 1003871232. Its totient is φ = 103680000.

The previous prime is 398649959. The next prime is 398649967. The reversal of 398649966 is 669946893.

It is a happy number.

398649966 is a nontrivial binomial coefficient, being equal to C(28237, 2).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398649967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2202396 + ... + 2202576.

It is an arithmetic number, because the mean of its divisors is an integer number (7842744).

Almost surely, 2^398649966 is an apocalyptic number.

398649966 is the 28236-th triangular number.

It is a practical number, because each smaller number is the sum of distinct divisors of 398649966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (501935616).

398649966 is an abundant number, since it is smaller than the sum of its proper divisors (605221266).

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

398649966 is a wasteful number, since it uses less digits than its factorization.

398649966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378.

The product of its digits is 15116544, while the sum is 60.

The square root of 398649966 is about 19966.2206238437. The cubic root of 398649966 is about 735.9764374447.

It can be divided in two parts, 39864 and 9966, that multiplied together give a square (397284624 = 19932²).

The spelling of 398649966 in words is "three hundred ninety-eight million, six hundred forty-nine thousand, nine hundred sixty-six".