19901989 has 4 divisors (see below), whose sum is σ = 20141856. Its totient is φ = 19662124.

The previous prime is 19901963. The next prime is 19902011. The reversal of 19901989 is 98910991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19901989 - 2⁵ = 19901957 is a prime.

It is a super-2 number, since 2×19901989² = 792178332312242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19901909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119809 + ... + 119974.

It is an arithmetic number, because the mean of its divisors is an integer number (5035464).

Almost surely, 2^19901989 is an apocalyptic number.

It is an amenable number.

19901989 is a deficient number, since it is larger than the sum of its proper divisors (239867).

19901989 is an equidigital number, since it uses as much as digits as its factorization.

19901989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239866.

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

The square root of 19901989 is about 4461.1645340651. The cubic root of 19901989 is about 270.9976307305.

The spelling of 19901989 in words is "nineteen million, nine hundred one thousand, nine hundred eighty-nine".