261421664 has 36 divisors (see below), whose sum is σ = 598705884. Its totient is φ = 112037184.

The previous prime is 261421637. The next prime is 261421673. The reversal of 261421664 is 466124162.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 261421664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 81794 + ... + 84929.

It is an arithmetic number, because the mean of its divisors is an integer number (16630719).

Almost surely, 2^261421664 is an apocalyptic number.

It is an amenable number.

261421664 is an abundant number, since it is smaller than the sum of its proper divisors (337284220).

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

261421664 is a wasteful number, since it uses less digits than its factorization.

261421664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166747 (or 166732 counting only the distinct ones).

The product of its digits is 13824, while the sum is 32.

The square root of 261421664 is about 16168.5393279665. The cubic root of 261421664 is about 639.4116207019.

The spelling of 261421664 in words is "two hundred sixty-one million, four hundred twenty-one thousand, six hundred sixty-four".