261190809 has 24 divisors (see below), whose sum is σ = 412776000. Its totient is φ = 157835040.

The previous prime is 261190789. The next prime is 261190819. The reversal of 261190809 is 908091162.

It is not a de Polignac number, because 261190809 - 2¹⁵ = 261158041 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261190819) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31867 + ... + 39215.

It is an arithmetic number, because the mean of its divisors is an integer number (17199000).

Almost surely, 2^261190809 is an apocalyptic number.

It is an amenable number.

261190809 is a deficient number, since it is larger than the sum of its proper divisors (151585191).

261190809 is a wasteful number, since it uses less digits than its factorization.

261190809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7725 (or 7722 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 261190809 is about 16161.3987327830. The cubic root of 261190809 is about 639.2233490805.

The spelling of 261190809 in words is "two hundred sixty-one million, one hundred ninety thousand, eight hundred nine".