17961881 has 10 divisors (see below), whose sum is σ = 20957082. Its totient is φ = 15393840.

The previous prime is 17961871. The next prime is 17961887. The reversal of 17961881 is 18816971.

It can be written as a sum of positive squares in only one way, i.e., 17347225 + 614656 = 4165^2 + 784^2 .

It is not a de Polignac number, because 17961881 - 2²² = 13767577 is a prime.

It is a super-2 number, since 2×17961881² = 645258338116322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17961887) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1340 + ... + 6141.

Almost surely, 2^17961881 is an apocalyptic number.

It is an amenable number.

17961881 is a deficient number, since it is larger than the sum of its proper divisors (2995201).

17961881 is an frugal number, since it uses more digits than its factorization.

17961881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7509 (or 7488 counting only the distinct ones).

The product of its digits is 24192, while the sum is 41.

The square root of 17961881 is about 4238.1459389691. The cubic root of 17961881 is about 261.8890085978.

The spelling of 17961881 in words is "seventeen million, nine hundred sixty-one thousand, eight hundred eighty-one".