66876721 has 4 divisors (see below), whose sum is σ = 66968692. Its totient is φ = 66784752.

The previous prime is 66876707. The next prime is 66876737. The reversal of 66876721 is 12767866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12767866 = 2 ⋅6383933.

It can be written as a sum of positive squares in 2 ways, for example, as 35236096 + 31640625 = 5936^2 + 5625^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66876721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66876701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44886 + ... + 46351.

It is an arithmetic number, because the mean of its divisors is an integer number (16742173).

Almost surely, 2^66876721 is an apocalyptic number.

It is an amenable number.

66876721 is a deficient number, since it is larger than the sum of its proper divisors (91971).

66876721 is an equidigital number, since it uses as much as digits as its factorization.

66876721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91970.

The product of its digits is 169344, while the sum is 43.

The square root of 66876721 is about 8177.8188412314. The cubic root of 66876721 is about 405.9055508414.

The spelling of 66876721 in words is "sixty-six million, eight hundred seventy-six thousand, seven hundred twenty-one".