66663623 has 4 divisors (see below), whose sum is σ = 71791608. Its totient is φ = 61535640.

The previous prime is 66663617. The next prime is 66663659. The reversal of 66663623 is 32636666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32636666 = 2 ⋅16318333.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66663623 is a prime.

It is a super-2 number, since 2×66663623² = 8888077262972258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66660623) 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, 2563973 + ... + 2563998.

It is an arithmetic number, because the mean of its divisors is an integer number (17947902).

Almost surely, 2^66663623 is an apocalyptic number.

66663623 is a deficient number, since it is larger than the sum of its proper divisors (5127985).

66663623 is a wasteful number, since it uses less digits than its factorization.

66663623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5127984.

The product of its digits is 139968, while the sum is 38.

The square root of 66663623 is about 8164.7794213928. The cubic root of 66663623 is about 405.4739622125.

The spelling of 66663623 in words is "sixty-six million, six hundred sixty-three thousand, six hundred twenty-three".