399781791 has 64 divisors (see below), whose sum is σ = 649728000. Its totient is φ = 242161920.

The previous prime is 399781777. The next prime is 399781813. The reversal of 399781791 is 197187993.

It is not a de Polignac number, because 399781791 - 2¹⁴ = 399765407 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399781771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1422571 + ... + 1422851.

It is an arithmetic number, because the mean of its divisors is an integer number (10152000).

Almost surely, 2^399781791 is an apocalyptic number.

399781791 is a deficient number, since it is larger than the sum of its proper divisors (249946209).

399781791 is a wasteful number, since it uses less digits than its factorization.

399781791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421 (or 415 counting only the distinct ones).

The product of its digits is 857304, while the sum is 54.

The square root of 399781791 is about 19994.5440308100. The cubic root of 399781791 is about 736.6722938858.

The spelling of 399781791 in words is "three hundred ninety-nine million, seven hundred eighty-one thousand, seven hundred ninety-one".