21920139 has 10 divisors (see below), whose sum is σ = 32745020. Its totient is φ = 14613372.

The previous prime is 21920113. The next prime is 21920141. The reversal of 21920139 is 93102912.

It is not a de Polignac number, because 21920139 - 2⁷ = 21920011 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21920179) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 135229 + ... + 135390.

It is an arithmetic number, because the mean of its divisors is an integer number (3274502).

Almost surely, 2^21920139 is an apocalyptic number.

21920139 is a deficient number, since it is larger than the sum of its proper divisors (10824881).

21920139 is an equidigital number, since it uses as much as digits as its factorization.

21920139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270631 (or 270622 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21920139 is about 4681.8948087286. The cubic root of 21920139 is about 279.8644709748.

The spelling of 21920139 in words is "twenty-one million, nine hundred twenty thousand, one hundred thirty-nine".