66712581 has 36 divisors (see below), whose sum is σ = 108939168. Its totient is φ = 39248352.

The previous prime is 66712559. The next prime is 66712603. The reversal of 66712581 is 18521766.

66712581 is a `hidden beast` number, since 6 + 6 + 71 + 2 + 581 = 666.

It is an interprime number because it is at equal distance from previous prime (66712559) and next prime (66712603).

It is not a de Polignac number, because 66712581 - 2⁵ = 66712549 is a prime.

It is a super-2 number, since 2×66712581² = 8901136927363122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66712181) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 34030 + ... + 35936.

It is an arithmetic number, because the mean of its divisors is an integer number (3026088).

Almost surely, 2^66712581 is an apocalyptic number.

It is an amenable number.

66712581 is a deficient number, since it is larger than the sum of its proper divisors (42226587).

66712581 is a wasteful number, since it uses less digits than its factorization.

66712581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1962 (or 1946 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 66712581 is about 8167.7769925482. The cubic root of 66712581 is about 405.5731984263.

The spelling of 66712581 in words is "sixty-six million, seven hundred twelve thousand, five hundred eighty-one".