21549139 has 8 divisors (see below), whose sum is σ = 21938688. Its totient is φ = 21162120.

The previous prime is 21549131. The next prime is 21549161. The reversal of 21549139 is 93194512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21549139 - 2³ = 21549131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21549131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25644 + ... + 26470.

It is an arithmetic number, because the mean of its divisors is an integer number (2742336).

Almost surely, 2^21549139 is an apocalyptic number.

21549139 is a deficient number, since it is larger than the sum of its proper divisors (389549).

21549139 is an equidigital number, since it uses as much as digits as its factorization.

21549139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1265.

The product of its digits is 9720, while the sum is 34.

The square root of 21549139 is about 4642.1050182003. The cubic root of 21549139 is about 278.2765694737.

The spelling of 21549139 in words is "twenty-one million, five hundred forty-nine thousand, one hundred thirty-nine".