17999881 has 2 divisors, whose sum is σ = 17999882. Its totient is φ = 17999880.

The previous prime is 17999879. The next prime is 17999899. The reversal of 17999881 is 18899971.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10758400 + 7241481 = 3280^2 + 2691^2 .

It is a cyclic number.

It is not a de Polignac number, because 17999881 - 2¹ = 17999879 is a prime.

It is a super-2 number, since 2×17999881² = 647991432028322, which contains 22 as substring.

Together with 17999879, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (17999801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8999940 + 8999941.

It is an arithmetic number, because the mean of its divisors is an integer number (8999941).

Almost surely, 2^17999881 is an apocalyptic number.

It is an amenable number.

17999881 is a deficient number, since it is larger than the sum of its proper divisors (1).

17999881 is an equidigital number, since it uses as much as digits as its factorization.

17999881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 52.

The square root of 17999881 is about 4242.6266628116. The cubic root of 17999881 is about 262.0735618859.

The spelling of 17999881 in words is "seventeen million, nine hundred ninety-nine thousand, eight hundred eighty-one".