17981399 has 2 divisors, whose sum is σ = 17981400. Its totient is φ = 17981398.

The previous prime is 17981357. The next prime is 17981413. The reversal of 17981399 is 99318971.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 17981399 - 2²⁴ = 1204183 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17981099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8990699 + 8990700.

It is an arithmetic number, because the mean of its divisors is an integer number (8990700).

Almost surely, 2^17981399 is an apocalyptic number.

17981399 is a deficient number, since it is larger than the sum of its proper divisors (1).

17981399 is an equidigital number, since it uses as much as digits as its factorization.

17981399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 17981399 is about 4240.4479716181. The cubic root of 17981399 is about 261.9838334721.

The spelling of 17981399 in words is "seventeen million, nine hundred eighty-one thousand, three hundred ninety-nine".