21989944 has 16 divisors (see below), whose sum is σ = 41416200. Its totient is φ = 10945632.

The previous prime is 21989941. The next prime is 21989953. The reversal of 21989944 is 44998912.

It is a super-3 number, since 3×21989944³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21989894 and 21989903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21989941) 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, 4239 + ... + 7870.

Almost surely, 2^21989944 is an apocalyptic number.

It is an amenable number.

21989944 is a deficient number, since it is larger than the sum of its proper divisors (19426256).

21989944 is a wasteful number, since it uses less digits than its factorization.

21989944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12342 (or 12338 counting only the distinct ones).

The product of its digits is 186624, while the sum is 46.

The square root of 21989944 is about 4689.3436640963. The cubic root of 21989944 is about 280.1612336689.

The spelling of 21989944 in words is "twenty-one million, nine hundred eighty-nine thousand, nine hundred forty-four".