661553536 has 32 divisors (see below), whose sum is σ = 1506217680. Its totient is φ = 283522560.

The previous prime is 661553527. The next prime is 661553561. The reversal of 661553536 is 635355166.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 368275 + ... + 370066.

Almost surely, 2^661553536 is an apocalyptic number.

It is an amenable number.

661553536 is an abundant number, since it is smaller than the sum of its proper divisors (844664144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661553536 is an equidigital number, since it uses as much as digits as its factorization.

661553536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738362 (or 738350 counting only the distinct ones).

The product of its digits is 243000, while the sum is 40.

The square root of 661553536 is about 25720.6830391419. The cubic root of 661553536 is about 871.3413650054.

The spelling of 661553536 in words is "six hundred sixty-one million, five hundred fifty-three thousand, five hundred thirty-six".