861561271 has 2 divisors, whose sum is σ = 861561272. Its totient is φ = 861561270.

The previous prime is 861561229. The next prime is 861561307. The reversal of 861561271 is 172165168.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 861561271 - 2⁷ = 861561143 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 861561271.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (861562271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430780635 + 430780636.

It is an arithmetic number, because the mean of its divisors is an integer number (430780636).

Almost surely, 2^861561271 is an apocalyptic number.

861561271 is a deficient number, since it is larger than the sum of its proper divisors (1).

861561271 is an equidigital number, since it uses as much as digits as its factorization.

861561271 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 37.

The square root of 861561271 is about 29352.3639763478. The cubic root of 861561271 is about 951.5436661282.

The spelling of 861561271 in words is "eight hundred sixty-one million, five hundred sixty-one thousand, two hundred seventy-one".