20989997 has 8 divisors (see below), whose sum is σ = 24816000. Its totient is φ = 17370864.

The previous prime is 20989987. The next prime is 20990023. The reversal of 20989997 is 79998902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20989997 - 2⁴ = 20989981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20989937) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51497 + ... + 51902.

It is an arithmetic number, because the mean of its divisors is an integer number (3102000).

Almost surely, 2^20989997 is an apocalyptic number.

It is an amenable number.

20989997 is a deficient number, since it is larger than the sum of its proper divisors (3826003).

20989997 is a wasteful number, since it uses less digits than its factorization.

20989997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103435.

The product of its (nonzero) digits is 734832, while the sum is 53.

The square root of 20989997 is about 4581.4841481773. The cubic root of 20989997 is about 275.8486050959.

The spelling of 20989997 in words is "twenty million, nine hundred eighty-nine thousand, nine hundred ninety-seven".