261511913968900 has 81 divisors (see below), whose sum is σ = 660133646033589. Its totient is φ = 89660839534560.

The previous prime is 261511913968859. The next prime is 261511913968931. The reversal of 261511913968900 is 9869319115162.

The square root of 261511913968900 is 16171330.

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., 94144289028804 + 167367624940096 = 9702798^2 + 12937064^2 .

It is a super-2 number, since 2×261511913968900² (a number of 30 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1131877591 + ... + 1132108609.

Almost surely, 2^{261511913968900} is an apocalyptic number.

261511913968900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

261511913968900 is the 16171330-th square number.

It is an amenable number.

261511913968900 is an abundant number, since it is smaller than the sum of its proper divisors (398621732064689).

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

261511913968900 is an frugal number, since it uses more digits than its factorization.

261511913968900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462066 (or 231033 counting only the distinct ones).

The product of its (nonzero) digits is 6298560, while the sum is 61.

The spelling of 261511913968900 in words is "two hundred sixty-one trillion, five hundred eleven billion, nine hundred thirteen million, nine hundred sixty-eight thousand, nine hundred".