399890640 has 40 divisors (see below), whose sum is σ = 1239661728. Its totient is φ = 106637440.

The previous prime is 399890633. The next prime is 399890641. The reversal of 399890640 is 46098993.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 399890640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399890641) 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, 832866 + ... + 833345.

Almost surely, 2^399890640 is an apocalyptic number.

399890640 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

399890640 is an abundant number, since it is smaller than the sum of its proper divisors (839771088).

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

399890640 is a wasteful number, since it uses less digits than its factorization.

399890640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1666227 (or 1666221 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 48.

The square root of 399890640 is about 19997.2658131056. The cubic root of 399890640 is about 736.7391459936.

The spelling of 399890640 in words is "three hundred ninety-nine million, eight hundred ninety thousand, six hundred forty".