66691564 has 12 divisors (see below), whose sum is σ = 116877600. Its totient is φ = 33297968.

The previous prime is 66691553. The next prime is 66691567. The reversal of 66691564 is 46519666.

It is a self number, because there is not a number n which added to its sum of digits gives 66691564.

It is not an unprimeable number, because it can be changed into a prime (66691567) 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, 8719 + ... + 14470.

It is an arithmetic number, because the mean of its divisors is an integer number (9739800).

Almost surely, 2^66691564 is an apocalyptic number.

It is an amenable number.

66691564 is a deficient number, since it is larger than the sum of its proper divisors (50186036).

66691564 is a wasteful number, since it uses less digits than its factorization.

66691564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23912 (or 23910 counting only the distinct ones).

The product of its digits is 233280, while the sum is 43.

The square root of 66691564 is about 8166.4903110210. The cubic root of 66691564 is about 405.5306036260.

The spelling of 66691564 in words is "sixty-six million, six hundred ninety-one thousand, five hundred sixty-four".