21808844 has 6 divisors (see below), whose sum is σ = 38165484. Its totient is φ = 10904420.

The previous prime is 21808837. The next prime is 21808859. The reversal of 21808844 is 44880812.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2726102 + ... + 2726109.

It is an arithmetic number, because the mean of its divisors is an integer number (6360914).

Almost surely, 2^21808844 is an apocalyptic number.

It is an amenable number.

21808844 is a deficient number, since it is larger than the sum of its proper divisors (16356640).

21808844 is a wasteful number, since it uses less digits than its factorization.

21808844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5452215 (or 5452213 counting only the distinct ones).

The product of its (nonzero) digits is 16384, while the sum is 35.

The square root of 21808844 is about 4669.9940042788. The cubic root of 21808844 is about 279.3900156420.

The spelling of 21808844 in words is "twenty-one million, eight hundred eight thousand, eight hundred forty-four".