645136388 has 48 divisors (see below), whose sum is σ = 1240614144. Its totient is φ = 291742080.

The previous prime is 645136343. The next prime is 645136397. The reversal of 645136388 is 883631546.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 726881 + ... + 727767.

It is an arithmetic number, because the mean of its divisors is an integer number (25846128).

Almost surely, 2^645136388 is an apocalyptic number.

It is an amenable number.

645136388 is a deficient number, since it is larger than the sum of its proper divisors (595477756).

645136388 is a wasteful number, since it uses less digits than its factorization.

645136388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1172 (or 1170 counting only the distinct ones).

The product of its digits is 414720, while the sum is 44.

The square root of 645136388 is about 25399.5351925975. The cubic root of 645136388 is about 864.0731551712.

The spelling of 645136388 in words is "six hundred forty-five million, one hundred thirty-six thousand, three hundred eighty-eight".