21898644 has 12 divisors (see below), whose sum is σ = 51096864. Its totient is φ = 7299544.

The previous prime is 21898619. The next prime is 21898649. The reversal of 21898644 is 44689812.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21898596 and 21898605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21898649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 912432 + ... + 912455.

It is an arithmetic number, because the mean of its divisors is an integer number (4258072).

Almost surely, 2^21898644 is an apocalyptic number.

It is an amenable number.

21898644 is an abundant number, since it is smaller than the sum of its proper divisors (29198220).

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

21898644 is a wasteful number, since it uses less digits than its factorization.

21898644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1824894 (or 1824892 counting only the distinct ones).

The product of its digits is 110592, while the sum is 42.

The square root of 21898644 is about 4679.5987007435. The cubic root of 21898644 is about 279.7729622148.

The spelling of 21898644 in words is "twenty-one million, eight hundred ninety-eight thousand, six hundred forty-four".