399621988 has 6 divisors (see below), whose sum is σ = 699338486. Its totient is φ = 199810992.

The previous prime is 399621979. The next prime is 399622019. The reversal of 399621988 is 889126993.

It can be written as a sum of positive squares in only one way, i.e., 203005504 + 196616484 = 14248^2 + 14022^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49952745 + ... + 49952752.

Almost surely, 2^399621988 is an apocalyptic number.

It is an amenable number.

399621988 is a deficient number, since it is larger than the sum of its proper divisors (299716498).

399621988 is a wasteful number, since it uses less digits than its factorization.

399621988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99905501 (or 99905499 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 55.

The square root of 399621988 is about 19990.5474662401. The cubic root of 399621988 is about 736.5741252229.

The spelling of 399621988 in words is "three hundred ninety-nine million, six hundred twenty-one thousand, nine hundred eighty-eight".