261581216 has 24 divisors (see below), whose sum is σ = 554603364. Its totient is φ = 120729600.

The previous prime is 261581197. The next prime is 261581233. The reversal of 261581216 is 612185162.

It can be written as a sum of positive squares in 2 ways, for example, as 187690000 + 73891216 = 13700^2 + 8596^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 313985 + ... + 314816.

Almost surely, 2^261581216 is an apocalyptic number.

261581216 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

261581216 is an abundant number, since it is smaller than the sum of its proper divisors (293022148).

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

261581216 is a wasteful number, since it uses less digits than its factorization.

261581216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 628824 (or 628816 counting only the distinct ones).

The product of its digits is 5760, while the sum is 32.

The square root of 261581216 is about 16173.4726017637. The cubic root of 261581216 is about 639.5416770681.

The spelling of 261581216 in words is "two hundred sixty-one million, five hundred eighty-one thousand, two hundred sixteen".