661626556 has 12 divisors (see below), whose sum is σ = 1208187792. Its totient is φ = 316430048.

The previous prime is 661626551. The next prime is 661626593. The reversal of 661626556 is 655626166.

It is a super-2 number, since 2×661626556² = 875499399208842272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661626551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3595705 + ... + 3595888.

It is an arithmetic number, because the mean of its divisors is an integer number (100682316).

Almost surely, 2^661626556 is an apocalyptic number.

It is an amenable number.

661626556 is a deficient number, since it is larger than the sum of its proper divisors (546561236).

661626556 is a wasteful number, since it uses less digits than its factorization.

661626556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7191620 (or 7191618 counting only the distinct ones).

The product of its digits is 388800, while the sum is 43.

The square root of 661626556 is about 25722.1024801629. The cubic root of 661626556 is about 871.3734223785.

The spelling of 661626556 in words is "six hundred sixty-one million, six hundred twenty-six thousand, five hundred fifty-six".