261139956480 has 720 divisors, whose sum is σ = 1011129762720. Its totient is φ = 63971721216.

The previous prime is 261139956431. The next prime is 261139956491. The reversal of 261139956480 is 84659931162.

261139956480 is a `hidden beast` number, since 2 + 61 + 13 + 9 + 9 + 564 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 421873611 + ... + 421874229.

Almost surely, 2^261139956480 is an apocalyptic number.

261139956480 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 261139956480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (505564881360).

261139956480 is an abundant number, since it is smaller than the sum of its proper divisors (749989806240).

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

261139956480 is a wasteful number, since it uses less digits than its factorization.

261139956480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 978 (or 955 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 54.

The spelling of 261139956480 in words is "two hundred sixty-one billion, one hundred thirty-nine million, nine hundred fifty-six thousand, four hundred eighty".