271561981 has 4 divisors (see below), whose sum is σ = 278901532. Its totient is φ = 264222432.

The previous prime is 271561963. The next prime is 271561987. The reversal of 271561981 is 189165172.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 260305956 + 11256025 = 16134^2 + 3355^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-271561981 is a prime.

It is a super-2 number, since 2×271561981² = 147491819049288722, 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 (271561987) 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 in 3 ways as a sum of consecutive naturals, for example, 3669720 + ... + 3669793.

It is an arithmetic number, because the mean of its divisors is an integer number (69725383).

Almost surely, 2^271561981 is an apocalyptic number.

It is an amenable number.

271561981 is a deficient number, since it is larger than the sum of its proper divisors (7339551).

271561981 is an equidigital number, since it uses as much as digits as its factorization.

271561981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7339550.

The product of its digits is 30240, while the sum is 40.

The square root of 271561981 is about 16479.1377505014. The cubic root of 271561981 is about 647.5743764535.

The spelling of 271561981 in words is "two hundred seventy-one million, five hundred sixty-one thousand, nine hundred eighty-one".