261291831 has 4 divisors (see below), whose sum is σ = 348389112. Its totient is φ = 174194552.

The previous prime is 261291829. The next prime is 261291841. The reversal of 261291831 is 138192162.

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 261291831 - 2¹ = 261291829 is a prime.

It is a super-2 number, since 2×261291831² = 136546841894665122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261291792 and 261291801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261291841) 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, 43548636 + ... + 43548641.

It is an arithmetic number, because the mean of its divisors is an integer number (87097278).

Almost surely, 2^261291831 is an apocalyptic number.

261291831 is a deficient number, since it is larger than the sum of its proper divisors (87097281).

261291831 is an equidigital number, since it uses as much as digits as its factorization.

261291831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87097280.

The product of its digits is 5184, while the sum is 33.

The square root of 261291831 is about 16164.5238408064. The cubic root of 261291831 is about 639.3057502668.

The spelling of 261291831 in words is "two hundred sixty-one million, two hundred ninety-one thousand, eight hundred thirty-one".