399515991 has 8 divisors (see below), whose sum is σ = 608786304. Its totient is φ = 228294840.

The previous prime is 399515989. The next prime is 399516001. The reversal of 399515991 is 199515993.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 399515991 - 2¹ = 399515989 is a prime.

It is a super-2 number, since 2×399515991² = 319226054129424162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399515971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9512265 + ... + 9512306.

It is an arithmetic number, because the mean of its divisors is an integer number (76098288).

Almost surely, 2^399515991 is an apocalyptic number.

399515991 is a deficient number, since it is larger than the sum of its proper divisors (209270313).

399515991 is a wasteful number, since it uses less digits than its factorization.

399515991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19024581.

The product of its digits is 492075, while the sum is 51.

The square root of 399515991 is about 19987.8961123976. The cubic root of 399515991 is about 736.5089957140.

The spelling of 399515991 in words is "three hundred ninety-nine million, five hundred fifteen thousand, nine hundred ninety-one".