20989251 has 6 divisors (see below), whose sum is σ = 30317820. Its totient is φ = 13992828.

The previous prime is 20989229. The next prime is 20989279. The reversal of 20989251 is 15298902.

It is not a de Polignac number, because 20989251 - 2⁶ = 20989187 is a prime.

It is a super-3 number, since 3×20989251³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (20989211) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1166061 + ... + 1166078.

It is an arithmetic number, because the mean of its divisors is an integer number (5052970).

Almost surely, 2^20989251 is an apocalyptic number.

20989251 is a deficient number, since it is larger than the sum of its proper divisors (9328569).

20989251 is a wasteful number, since it uses less digits than its factorization.

20989251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2332145 (or 2332142 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 20989251 is about 4581.4027327883. The cubic root of 20989251 is about 275.8453371028.

The spelling of 20989251 in words is "twenty million, nine hundred eighty-nine thousand, two hundred fifty-one".