399218820 has 576 divisors, whose sum is σ = 1663635456. Its totient is φ = 68935680.

The previous prime is 399218801. The next prime is 399218821. The reversal of 399218820 is 28812993.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399218821) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 17357329 + ... + 17357351.

It is an arithmetic number, because the mean of its divisors is an integer number (2888256).

Almost surely, 2^399218820 is an apocalyptic number.

399218820 is a gapful number since it is divisible by the number (30) 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 399218820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (831817728).

399218820 is an abundant number, since it is smaller than the sum of its proper divisors (1264416636).

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

399218820 is a wasteful number, since it uses less digits than its factorization.

399218820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100 (or 81 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 399218820 is about 19980.4609556436. The cubic root of 399218820 is about 736.3263385246.

The spelling of 399218820 in words is "three hundred ninety-nine million, two hundred eighteen thousand, eight hundred twenty".