66991608 has 48 divisors (see below), whose sum is σ = 186346680. Its totient is φ = 21726144.

The previous prime is 66991607. The next prime is 66991621. The reversal of 66991608 is 80619966.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66991601) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9910 + ... + 15237.

Almost surely, 2^66991608 is an apocalyptic number.

It is an amenable number.

66991608 is an abundant number, since it is smaller than the sum of its proper divisors (119355072).

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

66991608 is a wasteful number, since it uses less digits than its factorization.

66991608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25196 (or 25189 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The square root of 66991608 is about 8184.8401328309. The cubic root of 66991608 is about 406.1378518680.

The spelling of 66991608 in words is "sixty-six million, nine hundred ninety-one thousand, six hundred eight".