20418989 has 4 divisors (see below), whose sum is σ = 21620124. Its totient is φ = 19217856.

The previous prime is 20418973. The next prime is 20418991. The reversal of 20418989 is 98981402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6543364 + 13875625 = 2558^2 + 3725^2 .

It is a cyclic number.

It is not a de Polignac number, because 20418989 - 2⁴ = 20418973 is a prime.

It is a super-2 number, since 2×20418989² = 833870223564242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20418919) 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, 600542 + ... + 600575.

It is an arithmetic number, because the mean of its divisors is an integer number (5405031).

Almost surely, 2^20418989 is an apocalyptic number.

It is an amenable number.

20418989 is a deficient number, since it is larger than the sum of its proper divisors (1201135).

20418989 is a wasteful number, since it uses less digits than its factorization.

20418989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1201134.

The product of its (nonzero) digits is 41472, while the sum is 41.

The square root of 20418989 is about 4518.7375449344. The cubic root of 20418989 is about 273.3241954444.

The spelling of 20418989 in words is "twenty million, four hundred eighteen thousand, nine hundred eighty-nine".