17939989 has 2 divisors, whose sum is σ = 17939990. Its totient is φ = 17939988.

The previous prime is 17939963. The next prime is 17940007. The reversal of 17939989 is 98993971.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17892900 + 47089 = 4230^2 + 217^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-17939989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17939189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8969994 + 8969995.

It is an arithmetic number, because the mean of its divisors is an integer number (8969995).

Almost surely, 2^17939989 is an apocalyptic number.

It is an amenable number.

17939989 is a deficient number, since it is larger than the sum of its proper divisors (1).

17939989 is an equidigital number, since it uses as much as digits as its factorization.

17939989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 55.

The square root of 17939989 is about 4235.5624183808. The cubic root of 17939989 is about 261.7825682794.

The spelling of 17939989 in words is "seventeen million, nine hundred thirty-nine thousand, nine hundred eighty-nine".