76666666721 has 2 divisors, whose sum is σ = 76666666722. Its totient is φ = 76666666720.

The previous prime is 76666666717. The next prime is 76666666723. The reversal of 76666666721 is 12766666667.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56320782400 + 20345884321 = 237320^2 + 142639^2 .

It is a cyclic number.

It is not a de Polignac number, because 76666666721 - 2² = 76666666717 is a prime.

It is a super-2 number, since 2×76666666721² (a number of 23 digits) contains 22 as substring.

Together with 76666666723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (76666666723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38333333360 + 38333333361.

It is an arithmetic number, because the mean of its divisors is an integer number (38333333361).

Almost surely, 2^76666666721 is an apocalyptic number.

It is an amenable number.

76666666721 is a deficient number, since it is larger than the sum of its proper divisors (1).

76666666721 is an equidigital number, since it uses as much as digits as its factorization.

76666666721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27433728, while the sum is 59.

The spelling of 76666666721 in words is "seventy-six billion, six hundred sixty-six million, six hundred sixty-six thousand, seven hundred twenty-one".