66157691 has 4 divisors (see below), whose sum is σ = 66260592. Its totient is φ = 66054792.

The previous prime is 66157687. The next prime is 66157697. The reversal of 66157691 is 19675166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66157691 - 2² = 66157687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66157697) 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, 50480 + ... + 51773.

It is an arithmetic number, because the mean of its divisors is an integer number (16565148).

Almost surely, 2^66157691 is an apocalyptic number.

66157691 is a deficient number, since it is larger than the sum of its proper divisors (102901).

66157691 is a wasteful number, since it uses less digits than its factorization.

66157691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102900.

The product of its digits is 68040, while the sum is 41.

The square root of 66157691 is about 8133.7378246413. The cubic root of 66157691 is about 404.4455981839.

The spelling of 66157691 in words is "sixty-six million, one hundred fifty-seven thousand, six hundred ninety-one".