261857254464 has 224 divisors, whose sum is σ = 849251316480. Its totient is φ = 78606028800.

The previous prime is 261857254457. The next prime is 261857254469. The reversal of 261857254464 is 464452758162.

261857254464 is a `hidden beast` number, since 2 + 6 + 1 + 8 + 572 + 5 + 4 + 4 + 64 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 261857254464.

It is not an unprimeable number, because it can be changed into a prime (261857254469) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 778869 + ... + 1063179.

It is an arithmetic number, because the mean of its divisors is an integer number (3791300520).

Almost surely, 2^261857254464 is an apocalyptic number.

261857254464 is a gapful number since it is divisible by the number (24) 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 261857254464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (424625658240).

261857254464 is an abundant number, since it is smaller than the sum of its proper divisors (587394062016).

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

261857254464 is a wasteful number, since it uses less digits than its factorization.

261857254464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284386 (or 284370 counting only the distinct ones).

The product of its digits is 12902400, while the sum is 54.

The spelling of 261857254464 in words is "two hundred sixty-one billion, eight hundred fifty-seven million, two hundred fifty-four thousand, four hundred sixty-four".