261315216100 has 243 divisors, whose sum is σ = 628913405169. Its totient is φ = 94222540800.

The previous prime is 261315216023. The next prime is 261315216101. The reversal of 261315216100 is 1612513162.

The square root of 261315216100 is 511190.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 104061727396 + 157253488704 = 322586^2 + 396552^2 .

It is not an unprimeable number, because it can be changed into a prime (261315216101) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 2693971252 + ... + 2693971348.

Almost surely, 2^261315216100 is an apocalyptic number.

261315216100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

261315216100 is the 511190-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261315216100

261315216100 is an abundant number, since it is smaller than the sum of its proper divisors (367598189069).

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

261315216100 is a wasteful number, since it uses less digits than its factorization.

261315216100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 28.

Adding to 261315216100 its reverse (1612513162), we get a palindrome (262927729262).

The spelling of 261315216100 in words is "two hundred sixty-one billion, three hundred fifteen million, two hundred sixteen thousand, one hundred".