66518631 has 8 divisors (see below), whose sum is σ = 98546160. Its totient is φ = 44345736.

The previous prime is 66518629. The next prime is 66518633. The reversal of 66518631 is 13681566.

It is a happy number.

66518631 is a `hidden beast` number, since 6 + 6 + 5 + 18 + 631 = 666.

It is an interprime number because it is at equal distance from previous prime (66518629) and next prime (66518633).

It is not a de Polignac number, because 66518631 - 2¹ = 66518629 is a prime.

It is a super-2 number, since 2×66518631² = 8849456540228322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66518633) 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, 1231800 + ... + 1231853.

It is an arithmetic number, because the mean of its divisors is an integer number (12318270).

Almost surely, 2^66518631 is an apocalyptic number.

66518631 is a deficient number, since it is larger than the sum of its proper divisors (32027529).

66518631 is a wasteful number, since it uses less digits than its factorization.

66518631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2463662 (or 2463656 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 66518631 is about 8155.8954750536. The cubic root of 66518631 is about 405.1797830067.

The spelling of 66518631 in words is "sixty-six million, five hundred eighteen thousand, six hundred thirty-one".