77633721 has 45 divisors (see below), whose sum is σ = 128921023. Its totient is φ = 46522080.

The previous prime is 77633701. The next prime is 77633723. The reversal of 77633721 is 12733677.

The square root of 77633721 is 8811.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 14907321 + 62726400 = 3861^2 + 7920^2 .

It is not a de Polignac number, because 77633721 - 2⁹ = 77633209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77633723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 872245 + ... + 872333.

Almost surely, 2^77633721 is an apocalyptic number.

77633721 is the 8811-st square number.

77633721 is the 4406-th centered octagonal number.

It is an amenable number.

77633721 is a deficient number, since it is larger than the sum of its proper divisors (51287302).

77633721 is an equidigital number, since it uses as much as digits as its factorization.

77633721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212 (or 103 counting only the distinct ones).

The product of its digits is 37044, while the sum is 36.

The cubic root of 77633721 is about 426.5960214932.

Multiplying 77633721 by its sum of digits (36), we get a square (2794813956 = 52866²).

The spelling of 77633721 in words is "seventy-seven million, six hundred thirty-three thousand, seven hundred twenty-one".