264978785992561 has 9 divisors (see below), whose sum is σ = 267433877523393. Its totient is φ = 262546029913680.

The previous prime is 264978785992537. The next prime is 264978785992597. The reversal of 264978785992561 is 165299587879462.

The square root of 264978785992561 is 16278169.

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 6933115552561 + 258045670440000 = 2633081^2 + 16063800^2 .

It is not a de Polignac number, because 264978785992561 - 2¹⁹ = 264978785468273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (264978785990561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1774245751 + ... + 1774395091.

It is an arithmetic number, because the mean of its divisors is an integer number (29714875280377).

Almost surely, 2^{264978785992561} is an apocalyptic number.

264978785992561 is the 16278169-th square number.

264978785992561 is the 8139085-th centered octagonal number.

It is an amenable number.

264978785992561 is a deficient number, since it is larger than the sum of its proper divisors (2455091530832).

264978785992561 is an frugal number, since it uses more digits than its factorization.

264978785992561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298900 (or 149450 counting only the distinct ones).

The product of its digits is 32920473600, while the sum is 88.

The spelling of 264978785992561 in words is "two hundred sixty-four trillion, nine hundred seventy-eight billion, seven hundred eighty-five million, nine hundred ninety-two thousand, five hundred sixty-one".