261064320660 has 288 divisors, whose sum is σ = 933396976512. Its totient is φ = 58227932160.

The previous prime is 261064320659. The next prime is 261064320677. The reversal of 261064320660 is 66023460162.

261064320660 is a `hidden beast` number, since 2 + 6 + 1 + 0 + 643 + 2 + 0 + 6 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7885662 + ... + 7918698.

It is an arithmetic number, because the mean of its divisors is an integer number (3240961724).

Almost surely, 2^261064320660 is an apocalyptic number.

261064320660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261064320660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (466698488256).

261064320660 is an abundant number, since it is smaller than the sum of its proper divisors (672332655852).

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

261064320660 is a wasteful number, since it uses less digits than its factorization.

261064320660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33383 (or 33378 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The spelling of 261064320660 in words is "two hundred sixty-one billion, sixty-four million, three hundred twenty thousand, six hundred sixty".