21768844 has 12 divisors (see below), whose sum is σ = 38466064. Its totient is φ = 10778544.

The previous prime is 21768811. The next prime is 21768847. The reversal of 21768844 is 44886712.

It is a junction number, because it is equal to n+sod(n) for n = 21768797 and 21768806.

It is not an unprimeable number, because it can be changed into a prime (21768847) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26007 + ... + 26830.

Almost surely, 2^21768844 is an apocalyptic number.

It is an amenable number.

21768844 is a deficient number, since it is larger than the sum of its proper divisors (16697220).

21768844 is a wasteful number, since it uses less digits than its factorization.

21768844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52944 (or 52942 counting only the distinct ones).

The product of its digits is 86016, while the sum is 40.

The square root of 21768844 is about 4665.7093780046. The cubic root of 21768844 is about 279.2190996586.

The spelling of 21768844 in words is "twenty-one million, seven hundred sixty-eight thousand, eight hundred forty-four".