665520644 has 6 divisors (see below), whose sum is σ = 1164661134. Its totient is φ = 332760320.

The previous prime is 665520637. The next prime is 665520659. The reversal of 665520644 is 446025566.

It can be written as a sum of positive squares in only one way, i.e., 572166400 + 93354244 = 23920^2 + 9662^2 .

It is a junction number, because it is equal to n+sod(n) for n = 665520598 and 665520607.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83190077 + ... + 83190084.

It is an arithmetic number, because the mean of its divisors is an integer number (194110189).

Almost surely, 2^665520644 is an apocalyptic number.

It is an amenable number.

665520644 is a deficient number, since it is larger than the sum of its proper divisors (499140490).

665520644 is a wasteful number, since it uses less digits than its factorization.

665520644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166380165 (or 166380163 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 38.

The square root of 665520644 is about 25797.6867955249. The cubic root of 665520644 is about 873.0796061220.

The spelling of 665520644 in words is "six hundred sixty-five million, five hundred twenty thousand, six hundred forty-four".