261781536 has 24 divisors (see below), whose sum is σ = 687176784. Its totient is φ = 87260480.

The previous prime is 261781523. The next prime is 261781571. The reversal of 261781536 is 635187162.

It is a tau number, because it is divible by the number of its divisors (24).

It is a junction number, because it is equal to n+sod(n) for n = 261781494 and 261781503.

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 3 ways as a sum of consecutive naturals, for example, 1363350 + ... + 1363541.

It is an arithmetic number, because the mean of its divisors is an integer number (28632366).

Almost surely, 2^261781536 is an apocalyptic number.

It is an amenable number.

261781536 is an abundant number, since it is smaller than the sum of its proper divisors (425395248).

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

261781536 is a wasteful number, since it uses less digits than its factorization.

261781536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2726904 (or 2726896 counting only the distinct ones).

The product of its digits is 60480, while the sum is 39.

The square root of 261781536 is about 16179.6642734020. The cubic root of 261781536 is about 639.7048899846.

The spelling of 261781536 in words is "two hundred sixty-one million, seven hundred eighty-one thousand, five hundred thirty-six".