53504778721 has 27 divisors (see below), whose sum is σ = 57072759289. Its totient is φ = 50155626752.

The previous prime is 53504778673. The next prime is 53504778739. The reversal of 53504778721 is 12787740535.

It is a happy number.

The square root of 53504778721 is 231311.

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 37104390625 + 16400388096 = 192625^2 + 128064^2 .

It is not a de Polignac number, because 53504778721 - 2³⁵ = 19145040353 is a prime.

It is a super-2 number, since 2×53504778721² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (53504778751) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 473493561 + ... + 473493673.

Almost surely, 2^53504778721 is an apocalyptic number.

53504778721 is the 231311-st square number.

53504778721 is the 115656-th centered octagonal number.

It is an amenable number.

53504778721 is a deficient number, since it is larger than the sum of its proper divisors (3567980568).

53504778721 is an frugal number, since it uses more digits than its factorization.

53504778721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 1646400, while the sum is 49.

Multiplying 53504778721 by its sum of digits (49), we get a square (2621734157329 = 1619177²).

The spelling of 53504778721 in words is "fifty-three billion, five hundred four million, seven hundred seventy-eight thousand, seven hundred twenty-one".