643551604 has 6 divisors (see below), whose sum is σ = 1126215314. Its totient is φ = 321775800.

The previous prime is 643551593. The next prime is 643551653. The reversal of 643551604 is 406155346.

It can be written as a sum of positive squares in only one way, i.e., 418611600 + 224940004 = 20460^2 + 14998^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 643551604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80443947 + ... + 80443954.

Almost surely, 2^643551604 is an apocalyptic number.

It is an amenable number.

643551604 is a deficient number, since it is larger than the sum of its proper divisors (482663710).

643551604 is a wasteful number, since it uses less digits than its factorization.

643551604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160887905 (or 160887903 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 643551604 is about 25368.3189037035. The cubic root of 643551604 is about 863.3650402365.

The spelling of 643551604 in words is "six hundred forty-three million, five hundred fifty-one thousand, six hundred four".