76656721 has 2 divisors, whose sum is σ = 76656722. Its totient is φ = 76656720.

The previous prime is 76656667. The next prime is 76656731. The reversal of 76656721 is 12765667.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62489025 + 14167696 = 7905^2 + 3764^2 .

It is a cyclic number.

It is not a de Polignac number, because 76656721 - 2²³ = 68268113 is a prime.

It is not a weakly prime, because it can be changed into another prime (76656731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38328360 + 38328361.

It is an arithmetic number, because the mean of its divisors is an integer number (38328361).

Almost surely, 2^76656721 is an apocalyptic number.

It is an amenable number.

76656721 is a deficient number, since it is larger than the sum of its proper divisors (1).

76656721 is an equidigital number, since it uses as much as digits as its factorization.

76656721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 105840, while the sum is 40.

The square root of 76656721 is about 8755.3824017001. The cubic root of 76656721 is about 424.7989286464.

It can be divided in two parts, 76656 and 721, that added together give a palindrome (77377).

The spelling of 76656721 in words is "seventy-six million, six hundred fifty-six thousand, seven hundred twenty-one".