21544642 has 16 divisors (see below), whose sum is σ = 37380672. Its totient is φ = 9121680.

The previous prime is 21544631. The next prime is 21544669. The reversal of 21544642 is 24644512.

It is a self number, because there is not a number n which added to its sum of digits gives 21544642.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8109 + ... + 10432.

It is an arithmetic number, because the mean of its divisors is an integer number (2336292).

Almost surely, 2^21544642 is an apocalyptic number.

21544642 is a deficient number, since it is larger than the sum of its proper divisors (15836030).

21544642 is a wasteful number, since it uses less digits than its factorization.

21544642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18633.

The product of its digits is 7680, while the sum is 28.

The square root of 21544642 is about 4641.6206221534. The cubic root of 21544642 is about 278.2572106679.

The spelling of 21544642 in words is "twenty-one million, five hundred forty-four thousand, six hundred forty-two".