261918768400 has 45 divisors (see below), whose sum is σ = 629284433071. Its totient is φ = 104763413120.

The previous prime is 261918768329. The next prime is 261918768427. The reversal of 261918768400 is 4867819162.

The square root of 261918768400 is 511780.

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 27445886224 + 234472882176 = 165668^2 + 484224^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 10222806 + ... + 10248394.

Almost surely, 2^261918768400 is an apocalyptic number.

261918768400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

261918768400 is the 511780-th square number.

It is an amenable number.

261918768400 is an abundant number, since it is smaller than the sum of its proper divisors (367365664671).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261918768400 is an frugal number, since it uses more digits than its factorization.

261918768400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51196 (or 25596 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 52.

The spelling of 261918768400 in words is "two hundred sixty-one billion, nine hundred eighteen million, seven hundred sixty-eight thousand, four hundred".