261591431 has 4 divisors (see below), whose sum is σ = 261848664. Its totient is φ = 261334200.

The previous prime is 261591419. The next prime is 261591433. The reversal of 261591431 is 134195162.

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 261591431 - 2⁶ = 261591367 is a prime.

It is a super-2 number, since 2×261591431² = 136860153545255522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261591433) 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, 127085 + ... + 129126.

It is an arithmetic number, because the mean of its divisors is an integer number (65462166).

Almost surely, 2^261591431 is an apocalyptic number.

261591431 is a deficient number, since it is larger than the sum of its proper divisors (257233).

261591431 is a wasteful number, since it uses less digits than its factorization.

261591431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257232.

The product of its digits is 6480, while the sum is 32.

The square root of 261591431 is about 16173.7883935706. The cubic root of 261591431 is about 639.5500018671.

The spelling of 261591431 in words is "two hundred sixty-one million, five hundred ninety-one thousand, four hundred thirty-one".