21601139 has 16 divisors (see below), whose sum is σ = 25328640. Its totient is φ = 18040320.

The previous prime is 21601121. The next prime is 21601171. The reversal of 21601139 is 93110612.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21601139 - 2²⁰ = 20552563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21601189) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79574 + ... + 79844.

It is an arithmetic number, because the mean of its divisors is an integer number (1583040).

Almost surely, 2^21601139 is an apocalyptic number.

21601139 is a deficient number, since it is larger than the sum of its proper divisors (3727501).

21601139 is a wasteful number, since it uses less digits than its factorization.

21601139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 21601139 is about 4647.7025507233. The cubic root of 21601139 is about 278.5002250878.

The spelling of 21601139 in words is "twenty-one million, six hundred one thousand, one hundred thirty-nine".