646640264 has 8 divisors (see below), whose sum is σ = 1212450510. Its totient is φ = 323320128.

The previous prime is 646640261. The next prime is 646640273. The reversal of 646640264 is 462046646.

It can be written as a sum of positive squares in only one way, i.e., 596824900 + 49815364 = 24430^2 + 7058^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-5 number, since 5×646640264⁵ (a number of 45 digits) contains 55555 as substring.

It is not an unprimeable number, because it can be changed into a prime (646640261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40415009 + ... + 40415024.

Almost surely, 2^646640264 is an apocalyptic number.

It is an amenable number.

646640264 is a deficient number, since it is larger than the sum of its proper divisors (565810246).

646640264 is a wasteful number, since it uses less digits than its factorization.

646640264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80830039 (or 80830035 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 38.

The square root of 646640264 is about 25429.1223600029. The cubic root of 646640264 is about 864.7440471398.

The spelling of 646640264 in words is "six hundred forty-six million, six hundred forty thousand, two hundred sixty-four".