646405644 has 12 divisors (see below), whose sum is σ = 1508279864. Its totient is φ = 215468544.

The previous prime is 646405633. The next prime is 646405667. The reversal of 646405644 is 446504646.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26933557 + ... + 26933580.

Almost surely, 2^646405644 is an apocalyptic number.

It is an amenable number.

646405644 is an abundant number, since it is smaller than the sum of its proper divisors (861874220).

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

646405644 is a wasteful number, since it uses less digits than its factorization.

646405644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53867144 (or 53867142 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 39.

The square root of 646405644 is about 25424.5087268171. The cubic root of 646405644 is about 864.6394496780.

The spelling of 646405644 in words is "six hundred forty-six million, four hundred five thousand, six hundred forty-four".