66564951 has 4 divisors (see below), whose sum is σ = 88753272. Its totient is φ = 44376632.

The previous prime is 66564943. The next prime is 66564973. The reversal of 66564951 is 15946566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66564951 - 2³ = 66564943 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66564941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11094156 + ... + 11094161.

It is an arithmetic number, because the mean of its divisors is an integer number (22188318).

Almost surely, 2^66564951 is an apocalyptic number.

66564951 is a deficient number, since it is larger than the sum of its proper divisors (22188321).

66564951 is a wasteful number, since it uses less digits than its factorization.

66564951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22188320.

The product of its digits is 194400, while the sum is 42.

The square root of 66564951 is about 8158.7346445389. The cubic root of 66564951 is about 405.2738096608.

The spelling of 66564951 in words is "sixty-six million, five hundred sixty-four thousand, nine hundred fifty-one".