21898444 has 6 divisors (see below), whose sum is σ = 38322284. Its totient is φ = 10949220.

The previous prime is 21898441. The next prime is 21898447. The reversal of 21898444 is 44489812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21898441) and next prime (21898447).

It is a super-2 number, since 2×21898444² = 959083699242272, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21898397 and 21898406.

It is not an unprimeable number, because it can be changed into a prime (21898441) 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 as a sum of consecutive naturals, namely, 2737302 + ... + 2737309.

Almost surely, 2^21898444 is an apocalyptic number.

It is an amenable number.

21898444 is a deficient number, since it is larger than the sum of its proper divisors (16423840).

21898444 is a wasteful number, since it uses less digits than its factorization.

21898444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5474615 (or 5474613 counting only the distinct ones).

The product of its digits is 73728, while the sum is 40.

The square root of 21898444 is about 4679.5773313409. The cubic root of 21898444 is about 279.7721104914.

The spelling of 21898444 in words is "twenty-one million, eight hundred ninety-eight thousand, four hundred forty-four".