21921144 has 32 divisors (see below), whose sum is σ = 62632320. Its totient is φ = 6263136.

The previous prime is 21921121. The next prime is 21921167. The reversal of 21921144 is 44112912.

It is an interprime number because it is at equal distance from previous prime (21921121) and next prime (21921167).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65074 + ... + 65409.

It is an arithmetic number, because the mean of its divisors is an integer number (1957260).

Almost surely, 2^21921144 is an apocalyptic number.

21921144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21921144 is an abundant number, since it is smaller than the sum of its proper divisors (40711176).

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

21921144 is a wasteful number, since it uses less digits than its factorization.

21921144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130499 (or 130495 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 21921144 is about 4682.0021358389. The cubic root of 21921144 is about 279.8687480081.

The spelling of 21921144 in words is "twenty-one million, nine hundred twenty-one thousand, one hundred forty-four".