261815564 has 6 divisors (see below), whose sum is σ = 458177244. Its totient is φ = 130907780.

The previous prime is 261815563. The next prime is 261815579. The reversal of 261815564 is 465518162.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (261815563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32726942 + ... + 32726949.

It is an arithmetic number, because the mean of its divisors is an integer number (76362874).

Almost surely, 2^261815564 is an apocalyptic number.

It is an amenable number.

261815564 is a deficient number, since it is larger than the sum of its proper divisors (196361680).

261815564 is a wasteful number, since it uses less digits than its factorization.

261815564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65453895 (or 65453893 counting only the distinct ones).

The product of its digits is 57600, while the sum is 38.

The square root of 261815564 is about 16180.7158061688. The cubic root of 261815564 is about 639.7326063968.

The spelling of 261815564 in words is "two hundred sixty-one million, eight hundred fifteen thousand, five hundred sixty-four".