77860721 has 2 divisors, whose sum is σ = 77860722. Its totient is φ = 77860720.

The previous prime is 77860709. The next prime is 77860733. The reversal of 77860721 is 12706877.

It is a balanced prime because it is at equal distance from previous prime (77860709) and next prime (77860733).

It can be written as a sum of positive squares in only one way, i.e., 70896400 + 6964321 = 8420^2 + 2639^2 .

It is a cyclic number.

It is not a de Polignac number, because 77860721 - 2²⁶ = 10751857 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (77862721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38930360 + 38930361.

It is an arithmetic number, because the mean of its divisors is an integer number (38930361).

Almost surely, 2^77860721 is an apocalyptic number.

It is an amenable number.

77860721 is a deficient number, since it is larger than the sum of its proper divisors (1).

77860721 is an equidigital number, since it uses as much as digits as its factorization.

77860721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32928, while the sum is 38.

The square root of 77860721 is about 8823.8722225563. The cubic root of 77860721 is about 427.0114039884.

The spelling of 77860721 in words is "seventy-seven million, eight hundred sixty thousand, seven hundred twenty-one".