77523821761 has 9 divisors (see below), whose sum is σ = 79472466979. Its totient is φ = 75621859600.

The previous prime is 77523821747. The next prime is 77523821783. The reversal of 77523821761 is 16712832577.

It is a happy number.

The square root of 77523821761 is 278431.

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., 3735532161 + 73788289600 = 61119^2 + 271640^2 .

It is not a de Polignac number, because 77523821761 - 2²⁹ = 76986950849 is a prime.

It is a super-2 number, since 2×77523821761² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77523821731) 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, 11412276 + ... + 11419066.

Almost surely, 2^77523821761 is an apocalyptic number.

77523821761 is the 278431-st square number.

77523821761 is the 139216-th centered octagonal number.

It is an amenable number.

77523821761 is a deficient number, since it is larger than the sum of its proper divisors (1948645218).

77523821761 is an frugal number, since it uses more digits than its factorization.

77523821761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13664 (or 6832 counting only the distinct ones).

The product of its digits is 987840, while the sum is 49.

Multiplying 77523821761 by its sum of digits (49), we get a square (3798667266289 = 1949017²).

The spelling of 77523821761 in words is "seventy-seven billion, five hundred twenty-three million, eight hundred twenty-one thousand, seven hundred sixty-one".