261243864 has 48 divisors (see below), whose sum is σ = 808613520. Its totient is φ = 74640960.

The previous prime is 261243847. The next prime is 261243869. The reversal of 261243864 is 468342162.

261243864 is a `hidden beast` number, since 2 + 612 + 4 + 38 + 6 + 4 = 666.

261243864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261243869) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 258667 + ... + 259674.

It is an arithmetic number, because the mean of its divisors is an integer number (16846115).

Almost surely, 2^261243864 is an apocalyptic number.

261243864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

261243864 is an abundant number, since it is smaller than the sum of its proper divisors (547369656).

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

261243864 is a wasteful number, since it uses less digits than its factorization.

261243864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518360 (or 518353 counting only the distinct ones).

The product of its digits is 55296, while the sum is 36.

The square root of 261243864 is about 16163.0400605827. The cubic root of 261243864 is about 639.2666274011.

The spelling of 261243864 in words is "two hundred sixty-one million, two hundred forty-three thousand, eight hundred sixty-four".