261815136 has 96 divisors (see below), whose sum is σ = 789264000. Its totient is φ = 75156480.

The previous prime is 261815123. The next prime is 261815143. The reversal of 261815136 is 631518162.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 261815097 and 261815106.

It is a congruent number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 13540 + ... + 26588.

It is an arithmetic number, because the mean of its divisors is an integer number (8221500).

Almost surely, 2^261815136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261815136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (394632000).

261815136 is an abundant number, since it is smaller than the sum of its proper divisors (527448864).

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

261815136 is a wasteful number, since it uses less digits than its factorization.

261815136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13092 (or 13084 counting only the distinct ones).

The product of its digits is 8640, while the sum is 33.

The square root of 261815136 is about 16180.7025805433. The cubic root of 261815136 is about 639.7322577981.

The spelling of 261815136 in words is "two hundred sixty-one million, eight hundred fifteen thousand, one hundred thirty-six".