261138864 has 40 divisors (see below), whose sum is σ = 770982400. Its totient is φ = 74611008.

The previous prime is 261138847. The next prime is 261138919. The reversal of 261138864 is 468831162.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 388264 + ... + 388935.

It is an arithmetic number, because the mean of its divisors is an integer number (19274560).

Almost surely, 2^261138864 is an apocalyptic number.

261138864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

261138864 is an abundant number, since it is smaller than the sum of its proper divisors (509843536).

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

261138864 is a wasteful number, since it uses less digits than its factorization.

261138864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 777217 (or 777211 counting only the distinct ones).

The product of its digits is 55296, while the sum is 39.

The square root of 261138864 is about 16159.7915828144. The cubic root of 261138864 is about 639.1809705368.

The spelling of 261138864 in words is "two hundred sixty-one million, one hundred thirty-eight thousand, eight hundred sixty-four".