77195621281 has 9 divisors (see below), whose sum is σ = 77940912441. Its totient is φ = 76457397744.

The previous prime is 77195621273. The next prime is 77195621297. The reversal of 77195621281 is 18212659177.

The square root of 77195621281 is 277841.

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 32775843681 + 44419777600 = 181041^2 + 210760^2 .

It is not a de Polignac number, because 77195621281 - 2³ = 77195621273 is a prime.

It is a super-2 number, since 2×77195621281² (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 (77195621201) 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, 30283395 + ... + 30285943.

Almost surely, 2^77195621281 is an apocalyptic number.

77195621281 is the 277841-st square number.

77195621281 is the 138921-st centered octagonal number.

It is an amenable number.

77195621281 is a deficient number, since it is larger than the sum of its proper divisors (745291160).

77195621281 is an frugal number, since it uses more digits than its factorization.

77195621281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5316 (or 2658 counting only the distinct ones).

The product of its digits is 423360, while the sum is 49.

Multiplying 77195621281 by its sum of digits (49), we get a square (3782585442769 = 1944887²).

The spelling of 77195621281 in words is "seventy-seven billion, one hundred ninety-five million, six hundred twenty-one thousand, two hundred eighty-one".