636634640 has 40 divisors (see below), whose sum is σ = 1485570840. Its totient is φ = 253725696.

The previous prime is 636634633. The next prime is 636634697. The reversal of 636634640 is 46436636.

It can be written as a sum of positive squares in 4 ways, for example, as 3810304 + 632824336 = 1952^2 + 25156^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 636634594 and 636634603.

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, 7796 + ... + 36524.

It is an arithmetic number, because the mean of its divisors is an integer number (37139271).

Almost surely, 2^636634640 is an apocalyptic number.

It is an amenable number.

636634640 is an abundant number, since it is smaller than the sum of its proper divisors (848936200).

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

636634640 is a wasteful number, since it uses less digits than its factorization.

636634640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29019 (or 29013 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 38.

The square root of 636634640 is about 25231.6198449485. The cubic root of 636634640 is about 860.2607105731.

The spelling of 636634640 in words is "six hundred thirty-six million, six hundred thirty-four thousand, six hundred forty".