661688624 has 10 divisors (see below), whose sum is σ = 1282021740. Its totient is φ = 330844304.

The previous prime is 661688593. The next prime is 661688641. The reversal of 661688624 is 426886166.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20677754 + ... + 20677785.

It is an arithmetic number, because the mean of its divisors is an integer number (128202174).

Almost surely, 2^661688624 is an apocalyptic number.

It is an amenable number.

661688624 is a deficient number, since it is larger than the sum of its proper divisors (620333116).

661688624 is a wasteful number, since it uses less digits than its factorization.

661688624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41355547 (or 41355541 counting only the distinct ones).

The product of its digits is 663552, while the sum is 47.

The square root of 661688624 is about 25723.3089628842. The cubic root of 661688624 is about 871.4006697303.

The spelling of 661688624 in words is "six hundred sixty-one million, six hundred eighty-eight thousand, six hundred twenty-four".