77390721 has 10 divisors (see below), whose sum is σ = 115608482. Its totient is φ = 51593760.

The previous prime is 77390711. The next prime is 77390737. The reversal of 77390721 is 12709377.

It can be written as a sum of positive squares in only one way, i.e., 42107121 + 35283600 = 6489^2 + 5940^2 .

It is not a de Polignac number, because 77390721 - 2¹⁵ = 77357953 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (77390701) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 477640 + ... + 477801.

Almost surely, 2^77390721 is an apocalyptic number.

It is an amenable number.

77390721 is a deficient number, since it is larger than the sum of its proper divisors (38217761).

77390721 is an equidigital number, since it uses as much as digits as its factorization.

77390721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 955453 (or 955444 counting only the distinct ones).

The product of its (nonzero) digits is 18522, while the sum is 36.

The square root of 77390721 is about 8797.1996112399. The cubic root of 77390721 is about 426.1504626212.

The spelling of 77390721 in words is "seventy-seven million, three hundred ninety thousand, seven hundred twenty-one".