390721924 has 12 divisors (see below), whose sum is σ = 702243724. Its totient is φ = 190080864.

The previous prime is 390721889. The next prime is 390721927. The reversal of 390721924 is 429127093.

It can be written as a sum of positive squares in 2 ways, for example, as 290361600 + 100360324 = 17040^2 + 10018^2 .

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (390721927) 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, 1319859 + ... + 1320154.

Almost surely, 2^390721924 is an apocalyptic number.

It is an amenable number.

390721924 is a deficient number, since it is larger than the sum of its proper divisors (311521800).

390721924 is a wasteful number, since it uses less digits than its factorization.

390721924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2640054 (or 2640052 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 390721924 is about 19766.6872287695. The cubic root of 390721924 is about 731.0648898190.

The spelling of 390721924 in words is "three hundred ninety million, seven hundred twenty-one thousand, nine hundred twenty-four".