646780656 has 40 divisors (see below), whose sum is σ = 1699176960. Its totient is φ = 211938496.

The previous prime is 646780637. The next prime is 646780661. The reversal of 646780656 is 656087646.

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

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, 111360 + ... + 117023.

It is an arithmetic number, because the mean of its divisors is an integer number (42479424).

Almost surely, 2^646780656 is an apocalyptic number.

It is an amenable number.

646780656 is an abundant number, since it is smaller than the sum of its proper divisors (1052396304).

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

646780656 is a wasteful number, since it uses less digits than its factorization.

646780656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228453 (or 228447 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 48.

The square root of 646780656 is about 25431.8826672348. The cubic root of 646780656 is about 864.8066241078.

The spelling of 646780656 in words is "six hundred forty-six million, seven hundred eighty thousand, six hundred fifty-six".