16989991 has 2 divisors, whose sum is σ = 16989992. Its totient is φ = 16989990.

The previous prime is 16989967. The next prime is 16989997. The reversal of 16989991 is 19998961.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16989991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16989997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8494995 + 8494996.

It is an arithmetic number, because the mean of its divisors is an integer number (8494996).

Almost surely, 2^16989991 is an apocalyptic number.

16989991 is a deficient number, since it is larger than the sum of its proper divisors (1).

16989991 is an equidigital number, since it uses as much as digits as its factorization.

16989991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 314928, while the sum is 52.

The square root of 16989991 is about 4121.8916773734. The cubic root of 16989991 is about 257.0776864974.

The spelling of 16989991 in words is "sixteen million, nine hundred eighty-nine thousand, nine hundred ninety-one".