77457012721 has 9 divisors (see below), whose sum is σ = 85142065099. Its totient is φ = 70412683000.

The previous prime is 77457012719. The next prime is 77457012767. The reversal of 77457012721 is 12721075477.

The square root of 77457012721 is 278311.

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., 49867802721 + 27589210000 = 223311^2 + 166100^2 .

It is not a de Polignac number, because 77457012721 - 2¹ = 77457012719 is a prime.

It is a super-2 number, since 2×77457012721² (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 (77457012791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3048771 + ... + 3074071.

Almost surely, 2^77457012721 is an apocalyptic number.

77457012721 is the 278311-st square number.

77457012721 is the 139156-th centered octagonal number.

It is an amenable number.

77457012721 is a deficient number, since it is larger than the sum of its proper divisors (7685052378).

77457012721 is an frugal number, since it uses more digits than its factorization.

77457012721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50624 (or 25312 counting only the distinct ones).

The product of its (nonzero) digits is 192080, while the sum is 43.

The spelling of 77457012721 in words is "seventy-seven billion, four hundred fifty-seven million, twelve thousand, seven hundred twenty-one".