66564621 has 12 divisors (see below), whose sum is σ = 96352672. Its totient is φ = 44282376.

The previous prime is 66564583. The next prime is 66564629. The reversal of 66564621 is 12646566.

It is a happy number.

66564621 is a `hidden beast` number, since 6 + 6 + 5 + 646 + 2 + 1 = 666.

It is not a de Polignac number, because 66564621 - 2⁷ = 66564493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66564629) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3211 + ... + 11976.

Almost surely, 2^66564621 is an apocalyptic number.

It is an amenable number.

66564621 is a deficient number, since it is larger than the sum of its proper divisors (29788051).

66564621 is a wasteful number, since it uses less digits than its factorization.

66564621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15680 (or 15677 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The square root of 66564621 is about 8158.7144207896. The cubic root of 66564621 is about 405.2731399360.

The spelling of 66564621 in words is "sixty-six million, five hundred sixty-four thousand, six hundred twenty-one".