21291844 has 12 divisors (see below), whose sum is σ = 42583744. Its totient is φ = 9125064.

The previous prime is 21291839. The next prime is 21291847. The reversal of 21291844 is 44819212.

21291844 is an admirable number.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21291847) 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, 380184 + ... + 380239.

Almost surely, 2^21291844 is an apocalyptic number.

It is an amenable number.

21291844 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21291844 is a wasteful number, since it uses less digits than its factorization.

21291844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 760434 (or 760432 counting only the distinct ones).

The product of its digits is 4608, while the sum is 31.

The square root of 21291844 is about 4614.3086156000. The cubic root of 21291844 is about 277.1645987023.

The spelling of 21291844 in words is "twenty-one million, two hundred ninety-one thousand, eight hundred forty-four".