641392928 has 90 divisors (see below), whose sum is σ = 1427563305. Its totient is φ = 283662720.

The previous prime is 641392919. The next prime is 641392931. The reversal of 641392928 is 829293146.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 517471504 + 123921424 = 22748^2 + 11132^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=17908.

It is a super-2 number, since 2×641392928² = 822769776176826368, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a Duffinian number.

Its product of digits (186624) is a multiple of the sum of its prime factors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 17334926 + ... + 17334962.

Almost surely, 2^641392928 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 641392928

641392928 is an abundant number, since it is smaller than the sum of its proper divisors (786170377).

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

641392928 is an frugal number, since it uses more digits than its factorization.

641392928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128 (or 50 counting only the distinct ones).

The product of its digits is 186624, while the sum is 44.

The square root of 641392928 is about 25325.7364749774. The cubic root of 641392928 is about 862.3986255705.

The spelling of 641392928 in words is "six hundred forty-one million, three hundred ninety-two thousand, nine hundred twenty-eight".