20201989 has 4 divisors (see below), whose sum is σ = 20242656. Its totient is φ = 20161324.

The previous prime is 20201983. The next prime is 20202011. The reversal of 20201989 is 98910202.

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 20201989 - 2⁹ = 20201477 is a prime.

It is a super-2 number, since 2×20201989² = 816240719112242, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20201989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20201983) 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, 19579 + ... + 20584.

It is an arithmetic number, because the mean of its divisors is an integer number (5060664).

Almost surely, 2^20201989 is an apocalyptic number.

It is an amenable number.

20201989 is a deficient number, since it is larger than the sum of its proper divisors (40667).

20201989 is an equidigital number, since it uses as much as digits as its factorization.

20201989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40666.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 20201989 is about 4494.6622787480. The cubic root of 20201989 is about 272.3525066648.

The spelling of 20201989 in words is "twenty million, two hundred one thousand, nine hundred eighty-nine".