21855844 has 6 divisors (see below), whose sum is σ = 38247734. Its totient is φ = 10927920.

The previous prime is 21855839. The next prime is 21855877. The reversal of 21855844 is 44855812.

It can be written as a sum of positive squares in only one way, i.e., 12320100 + 9535744 = 3510^2 + 3088^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2731977 + ... + 2731984.

Almost surely, 2^21855844 is an apocalyptic number.

It is an amenable number.

21855844 is a deficient number, since it is larger than the sum of its proper divisors (16391890).

21855844 is a wasteful number, since it uses less digits than its factorization.

21855844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5463965 (or 5463963 counting only the distinct ones).

The product of its digits is 51200, while the sum is 37.

The square root of 21855844 is about 4675.0234224012. The cubic root of 21855844 is about 279.5905750870.

The spelling of 21855844 in words is "twenty-one million, eight hundred fifty-five thousand, eight hundred forty-four".