390396820 has 72 divisors (see below), whose sum is σ = 905669352. Its totient is φ = 141250560.

The previous prime is 390396761. The next prime is 390396821. The reversal of 390396820 is 28693093.

It can be written as a sum of positive squares in 4 ways, for example, as 82955664 + 307441156 = 9108^2 + 17534^2 .

It is a super-2 number, since 2×390396820² = 304819354132224800, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (390396821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 854032 + ... + 854488.

It is an arithmetic number, because the mean of its divisors is an integer number (12578741).

Almost surely, 2^390396820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 390396820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (452834676).

390396820 is an abundant number, since it is smaller than the sum of its proper divisors (515272532).

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

390396820 is a wasteful number, since it uses less digits than its factorization.

390396820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 841 (or 828 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 390396820 is about 19758.4619846789. The cubic root of 390396820 is about 730.8620703243.

The spelling of 390396820 in words is "three hundred ninety million, three hundred ninety-six thousand, eight hundred twenty".