261271531 has 2 divisors, whose sum is σ = 261271532. Its totient is φ = 261271530.

The previous prime is 261271523. The next prime is 261271553. The reversal of 261271531 is 135172162.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261271531 - 2³ = 261271523 is a prime.

It is a super-2 number, since 2×261271531² = 136525625822167922, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261271531.

It is not a weakly prime, because it can be changed into another prime (261271501) 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 as a sum of consecutive naturals, namely, 130635765 + 130635766.

It is an arithmetic number, because the mean of its divisors is an integer number (130635766).

Almost surely, 2^261271531 is an apocalyptic number.

261271531 is a deficient number, since it is larger than the sum of its proper divisors (1).

261271531 is an equidigital number, since it uses as much as digits as its factorization.

261271531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520, while the sum is 28.

The square root of 261271531 is about 16163.8959103305. The cubic root of 261271531 is about 639.2891937563.

The spelling of 261271531 in words is "two hundred sixty-one million, two hundred seventy-one thousand, five hundred thirty-one".