66123691 has 8 divisors (see below), whose sum is σ = 66927168. Its totient is φ = 65325000.

The previous prime is 66123679. The next prime is 66123703. The reversal of 66123691 is 19632166.

It is an interprime number because it is at equal distance from previous prime (66123679) and next prime (66123703).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66123691 - 2⁹ = 66123179 is a prime.

It is a super-2 number, since 2×66123691² = 8744685022926962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66123671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31876 + ... + 33886.

It is an arithmetic number, because the mean of its divisors is an integer number (8365896).

Almost surely, 2^66123691 is an apocalyptic number.

66123691 is a deficient number, since it is larger than the sum of its proper divisors (803477).

66123691 is a wasteful number, since it uses less digits than its factorization.

66123691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2393.

The product of its digits is 11664, while the sum is 34.

The square root of 66123691 is about 8131.6474960490. The cubic root of 66123691 is about 404.3763015963.

The spelling of 66123691 in words is "sixty-six million, one hundred twenty-three thousand, six hundred ninety-one".