643647632 has 10 divisors (see below), whose sum is σ = 1247067318. Its totient is φ = 321823808.

The previous prime is 643647611. The next prime is 643647647. The reversal of 643647632 is 236746346.

It can be written as a sum of positive squares in only one way, i.e., 588353536 + 55294096 = 24256^2 + 7436^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 643647632.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20113973 + ... + 20114004.

Almost surely, 2^643647632 is an apocalyptic number.

It is an amenable number.

643647632 is a deficient number, since it is larger than the sum of its proper divisors (603419686).

643647632 is a wasteful number, since it uses less digits than its factorization.

643647632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40227985 (or 40227979 counting only the distinct ones).

The product of its digits is 435456, while the sum is 41.

The square root of 643647632 is about 25370.2115087754. The cubic root of 643647632 is about 863.4079806391.

The spelling of 643647632 in words is "six hundred forty-three million, six hundred forty-seven thousand, six hundred thirty-two".