20989645 has 8 divisors (see below), whose sum is σ = 26669304. Its totient is φ = 15803904.

The previous prime is 20989627. The next prime is 20989651. The reversal of 20989645 is 54698902.

It can be written as a sum of positive squares in 4 ways, for example, as 1857769 + 19131876 = 1363^2 + 4374^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20989645 - 2⁵ = 20989613 is a prime.

It is a super-3 number, since 3×20989645³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 123384 + ... + 123553.

It is an arithmetic number, because the mean of its divisors is an integer number (3333663).

Almost surely, 2^20989645 is an apocalyptic number.

It is an amenable number.

20989645 is a deficient number, since it is larger than the sum of its proper divisors (5679659).

20989645 is a wasteful number, since it uses less digits than its factorization.

20989645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246959.

The product of its (nonzero) digits is 155520, while the sum is 43.

The square root of 20989645 is about 4581.4457325172. The cubic root of 20989645 is about 275.8470631035.

The spelling of 20989645 in words is "twenty million, nine hundred eighty-nine thousand, six hundred forty-five".