77373541921 has 9 divisors (see below), whose sum is σ = 83787100281. Its totient is φ = 71418393072.

The previous prime is 77373541907. The next prime is 77373541937. The reversal of 77373541921 is 12914537377.

It is a happy number.

The square root of 77373541921 is 278161.

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

It can be written as a sum of positive squares in 4 ways, for example, as 5570980321 + 71802561600 = 74639^2 + 267960^2 .

It is not a de Polignac number, because 77373541921 - 2²⁵ = 77339987489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77373551921) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3605395 + ... + 3626791.

It is an arithmetic number, because the mean of its divisors is an integer number (9309677809).

Almost surely, 2^77373541921 is an apocalyptic number.

77373541921 is the 278161-st square number.

77373541921 is the 139081-st centered octagonal number.

It is an amenable number.

77373541921 is a deficient number, since it is larger than the sum of its proper divisors (6413558360).

77373541921 is an frugal number, since it uses more digits than its factorization.

77373541921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42820 (or 21410 counting only the distinct ones).

The product of its digits is 1111320, while the sum is 49.

Multiplying 77373541921 by its sum of digits (49), we get a square (3791303554129 = 1947127²).

The spelling of 77373541921 in words is "seventy-seven billion, three hundred seventy-three million, five hundred forty-one thousand, nine hundred twenty-one".