261171604656000 has 768 divisors, whose sum is σ = 1000925942814720. Its totient is φ = 65032740864000.

The previous prime is 261171604655981. The next prime is 261171604656023. The reversal of 261171604656000 is 656406171162.

261171604656000 is a `hidden beast` number, since 2 + 6 + 1 + 1 + 71 + 60 + 465 + 60 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

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, 310475970 + ... + 311316030.

It is an arithmetic number, because the mean of its divisors is an integer number (1303288988040).

Almost surely, 2^{261171604656000} is an apocalyptic number.

261171604656000 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 261171604656000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (500462971407360).

261171604656000 is an abundant number, since it is smaller than the sum of its proper divisors (739754338158720).

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

261171604656000 is a wasteful number, since it uses less digits than its factorization.

261171604656000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 840240 (or 840215 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 261171604656000 in words is "two hundred sixty-one trillion, one hundred seventy-one billion, six hundred four million, six hundred fifty-six thousand".