21885139 has 4 divisors (see below), whose sum is σ = 21906256. Its totient is φ = 21864024.

The previous prime is 21885113. The next prime is 21885161. The reversal of 21885139 is 93158812.

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

It is a cyclic number.

It is not a de Polignac number, because 21885139 - 2⁵ = 21885107 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21885098 and 21885107.

It is not an unprimeable number, because it can be changed into a prime (21885439) 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, 8919 + ... + 11104.

It is an arithmetic number, because the mean of its divisors is an integer number (5476564).

Almost surely, 2^21885139 is an apocalyptic number.

21885139 is a deficient number, since it is larger than the sum of its proper divisors (21117).

21885139 is a wasteful number, since it uses less digits than its factorization.

21885139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21116.

The product of its digits is 17280, while the sum is 37.

The square root of 21885139 is about 4678.1555125925. The cubic root of 21885139 is about 279.7154379403.

The spelling of 21885139 in words is "twenty-one million, eight hundred eighty-five thousand, one hundred thirty-nine".