396978931 has 4 divisors (see below), whose sum is σ = 398974000. Its totient is φ = 394983864.

The previous prime is 396978929. The next prime is 396978947. The reversal of 396978931 is 139879693.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 396978931 - 2¹ = 396978929 is a prime.

It is a super-2 number, since 2×396978931² = 315184543315805522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (396978971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 997236 + ... + 997633.

It is an arithmetic number, because the mean of its divisors is an integer number (99743500).

Almost surely, 2^396978931 is an apocalyptic number.

396978931 is a deficient number, since it is larger than the sum of its proper divisors (1995069).

396978931 is a wasteful number, since it uses less digits than its factorization.

396978931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1995068.

The product of its digits is 2204496, while the sum is 55.

The square root of 396978931 is about 19924.3301267571. The cubic root of 396978931 is about 734.9466578593.

The spelling of 396978931 in words is "three hundred ninety-six million, nine hundred seventy-eight thousand, nine hundred thirty-one".