19891990 has 16 divisors (see below), whose sum is σ = 35938080. Its totient is φ = 7927360.

The previous prime is 19891981. The next prime is 19892003. The reversal of 19891990 is 9919891.

It is a self number, because there is not a number n which added to its sum of digits gives 19891990.

It is a congruent number.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 730 + ... + 6349.

It is an arithmetic number, because the mean of its divisors is an integer number (2246130).

Almost surely, 2^19891990 is an apocalyptic number.

19891990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19891990 is a deficient number, since it is larger than the sum of its proper divisors (16046090).

19891990 is a wasteful number, since it uses less digits than its factorization.

19891990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7367.

The product of its (nonzero) digits is 52488, while the sum is 46.

The square root of 19891990 is about 4460.0437217588. The cubic root of 19891990 is about 270.9522389653.

The spelling of 19891990 in words is "nineteen million, eight hundred ninety-one thousand, nine hundred ninety".