261153591 has 4 divisors (see below), whose sum is σ = 348204792. Its totient is φ = 174102392.

The previous prime is 261153589. The next prime is 261153601. The reversal of 261153591 is 195351162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261153591 - 2¹ = 261153589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261153521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43525596 + ... + 43525601.

It is an arithmetic number, because the mean of its divisors is an integer number (87051198).

Almost surely, 2^261153591 is an apocalyptic number.

261153591 is a deficient number, since it is larger than the sum of its proper divisors (87051201).

261153591 is an equidigital number, since it uses as much as digits as its factorization.

261153591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87051200.

The product of its digits is 8100, while the sum is 33.

The square root of 261153591 is about 16160.2472443957. The cubic root of 261153591 is about 639.1929859081.

The spelling of 261153591 in words is "two hundred sixty-one million, one hundred fifty-three thousand, five hundred ninety-one".