261161145 has 64 divisors (see below), whose sum is σ = 543037440. Its totient is φ = 116593344.

The previous prime is 261161141. The next prime is 261161161. The reversal of 261161145 is 541161162.

261161145 is a `hidden beast` number, since 2 + 6 + 1 + 1 + 611 + 45 = 666.

It is not a de Polignac number, because 261161145 - 2² = 261161141 is a prime.

It is a super-2 number, since 2×261161145² = 136410287315422050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (261161141) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 37422 + ... + 43848.

It is an arithmetic number, because the mean of its divisors is an integer number (8484960).

Almost surely, 2^261161145 is an apocalyptic number.

It is an amenable number.

261161145 is an abundant number, since it is smaller than the sum of its proper divisors (281876295).

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

261161145 is a wasteful number, since it uses less digits than its factorization.

261161145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6491 (or 6485 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 261161145 is about 16160.4809643773. The cubic root of 261161145 is about 639.1991488424.

It can be divided in two parts, 26116 and 1145, that added together give a triangular number (27261 = T₂₃₃).

The spelling of 261161145 in words is "two hundred sixty-one million, one hundred sixty-one thousand, one hundred forty-five".