17981961 has 16 divisors (see below), whose sum is σ = 25670400. Its totient is φ = 11162448.

The previous prime is 17981959. The next prime is 17981969. The reversal of 17981961 is 16918971.

It is not a de Polignac number, because 17981961 - 2¹ = 17981959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (17981969) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 690 + ... + 6036.

It is an arithmetic number, because the mean of its divisors is an integer number (1604400).

Almost surely, 2^17981961 is an apocalyptic number.

It is an amenable number.

17981961 is a deficient number, since it is larger than the sum of its proper divisors (7688439).

17981961 is a wasteful number, since it uses less digits than its factorization.

17981961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5428.

The product of its digits is 27216, while the sum is 42.

The square root of 17981961 is about 4240.5142376839. The cubic root of 17981961 is about 261.9865628367.

The spelling of 17981961 in words is "seventeen million, nine hundred eighty-one thousand, nine hundred sixty-one".