261306864 has 480 divisors, whose sum is σ = 1023267840. Its totient is φ = 62042112.

The previous prime is 261306833. The next prime is 261306883. The reversal of 261306864 is 468603162.

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, 11361157 + ... + 11361179.

It is an arithmetic number, because the mean of its divisors is an integer number (2131808).

Almost surely, 2^261306864 is an apocalyptic number.

261306864 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 261306864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (511633920).

261306864 is an abundant number, since it is smaller than the sum of its proper divisors (761960976).

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

261306864 is a wasteful number, since it uses less digits than its factorization.

261306864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94 (or 65 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 261306864 is about 16164.9888338965. The cubic root of 261306864 is about 639.3180105034.

The spelling of 261306864 in words is "two hundred sixty-one million, three hundred six thousand, eight hundred sixty-four".