21644342 has 8 divisors (see below), whose sum is σ = 32646432. Its totient is φ = 10762200.

The previous prime is 21644339. The next prime is 21644377. The reversal of 21644342 is 24344612.

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

It is a super-2 number, since 2×21644342² = 936955081225928, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29534 + ... + 30257.

It is an arithmetic number, because the mean of its divisors is an integer number (4080804).

Almost surely, 2^21644342 is an apocalyptic number.

21644342 is a deficient number, since it is larger than the sum of its proper divisors (11002090).

21644342 is a wasteful number, since it uses less digits than its factorization.

21644342 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59974.

The product of its digits is 4608, while the sum is 26.

The square root of 21644342 is about 4652.3480093389. The cubic root of 21644342 is about 278.6857713628.

Adding to 21644342 its reverse (24344612), we get a palindrome (45988954).

The spelling of 21644342 in words is "twenty-one million, six hundred forty-four thousand, three hundred forty-two".