66918621 has 32 divisors (see below), whose sum is σ = 113845248. Its totient is φ = 33949440.

The previous prime is 66918619. The next prime is 66918623. The reversal of 66918621 is 12681966.

It is an interprime number because it is at equal distance from previous prime (66918619) and next prime (66918623).

It is not a de Polignac number, because 66918621 - 2¹ = 66918619 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66918621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66918623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6565 + ... + 13301.

It is an arithmetic number, because the mean of its divisors is an integer number (3557664).

Almost surely, 2^66918621 is an apocalyptic number.

It is an amenable number.

66918621 is a deficient number, since it is larger than the sum of its proper divisors (46926627).

66918621 is a wasteful number, since it uses less digits than its factorization.

66918621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6801.

The product of its digits is 31104, while the sum is 39.

The square root of 66918621 is about 8180.3802478858. The cubic root of 66918621 is about 405.9903032620.

The spelling of 66918621 in words is "sixty-six million, nine hundred eighteen thousand, six hundred twenty-one".