66631 has 4 divisors (see below), whose sum is σ = 69552. Its totient is φ = 63712.

The previous prime is 66629. The next prime is 66643. The reversal of 66631 is 13666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13666 = 2 ⋅6833.

It is a cyclic number.

It is not a de Polignac number, because 66631 - 2¹ = 66629 is a prime.

It is a super-2 number, since 2×66631² = 8879380322, which contains 22 as substring.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66601) 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, 1426 + ... + 1471.

It is an arithmetic number, because the mean of its divisors is an integer number (17388).

2⁶⁶⁶³¹ is an apocalyptic number.

66631 is a deficient number, since it is larger than the sum of its proper divisors (2921).

66631 is a wasteful number, since it uses less digits than its factorization.

66631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2920.

The product of its digits is 648, while the sum is 22.

The square root of 66631 is about 258.1298123038. The cubic root of 66631 is about 40.5407809515.

The spelling of 66631 in words is "sixty-six thousand, six hundred thirty-one".