399393940 has 24 divisors (see below), whose sum is σ = 914975712. Its totient is φ = 145234080.

The previous prime is 399393931. The next prime is 399393959. The reversal of 399393940 is 49393993.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 907494 + ... + 907933.

It is an arithmetic number, because the mean of its divisors is an integer number (38123988).

Almost surely, 2^399393940 is an apocalyptic number.

It is an amenable number.

399393940 is an abundant number, since it is smaller than the sum of its proper divisors (515581772).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399393940 is a wasteful number, since it uses less digits than its factorization.

399393940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1815447 (or 1815445 counting only the distinct ones).

The product of its (nonzero) digits is 708588, while the sum is 49.

The square root of 399393940 is about 19984.8427564492. The cubic root of 399393940 is about 736.4339876068.

The spelling of 399393940 in words is "three hundred ninety-nine million, three hundred ninety-three thousand, nine hundred forty".