20981439 has 6 divisors (see below), whose sum is σ = 30306536. Its totient is φ = 13987620.

The previous prime is 20981407. The next prime is 20981447. The reversal of 20981439 is 93418902.

It is not a de Polignac number, because 20981439 - 2⁵ = 20981407 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 (20981449) 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, 1165627 + ... + 1165644.

Almost surely, 2^20981439 is an apocalyptic number.

20981439 is a deficient number, since it is larger than the sum of its proper divisors (9325097).

20981439 is a wasteful number, since it uses less digits than its factorization.

20981439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2331277 (or 2331274 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 20981439 is about 4580.5500761371. The cubic root of 20981439 is about 275.8111105174.

The spelling of 20981439 in words is "twenty million, nine hundred eighty-one thousand, four hundred thirty-nine".