661366672 has 10 divisors (see below), whose sum is σ = 1281397958. Its totient is φ = 330683328.

The previous prime is 661366669. The next prime is 661366681. The reversal of 661366672 is 276663166.

It can be written as a sum of positive squares in only one way, i.e., 391881616 + 269485056 = 19796^2 + 16416^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20667693 + ... + 20667724.

Almost surely, 2^661366672 is an apocalyptic number.

It is an amenable number.

661366672 is a deficient number, since it is larger than the sum of its proper divisors (620031286).

661366672 is a wasteful number, since it uses less digits than its factorization.

661366672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41335425 (or 41335419 counting only the distinct ones).

The product of its digits is 326592, while the sum is 43.

The square root of 661366672 is about 25717.0502196500. The cubic root of 661366672 is about 871.2593168885.

The spelling of 661366672 in words is "six hundred sixty-one million, three hundred sixty-six thousand, six hundred seventy-two".