261855031 has 4 divisors (see below), whose sum is σ = 268932232. Its totient is φ = 254777832.

The previous prime is 261855019. The next prime is 261855037. The reversal of 261855031 is 130558162.

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 261855031 - 2¹⁵ = 261822263 is a prime.

It is a super-2 number, since 2×261855031² = 137136114520021922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261854984 and 261855002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261855037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3538545 + ... + 3538618.

It is an arithmetic number, because the mean of its divisors is an integer number (67233058).

Almost surely, 2^261855031 is an apocalyptic number.

261855031 is a deficient number, since it is larger than the sum of its proper divisors (7077201).

261855031 is an equidigital number, since it uses as much as digits as its factorization.

261855031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7077200.

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 261855031 is about 16181.9353292491. The cubic root of 261855031 is about 639.7647499636.

The spelling of 261855031 in words is "two hundred sixty-one million, eight hundred fifty-five thousand, thirty-one".