21142944 has 72 divisors (see below), whose sum is σ = 62375040. Its totient is φ = 7045056.

The previous prime is 21142939. The next prime is 21142963. The reversal of 21142944 is 44924112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6417 + ... + 9135.

It is an arithmetic number, because the mean of its divisors is an integer number (866320).

Almost surely, 2^21142944 is an apocalyptic number.

21142944 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21142944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31187520).

21142944 is an abundant number, since it is smaller than the sum of its proper divisors (41232096).

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

21142944 is an equidigital number, since it uses as much as digits as its factorization.

21142944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2744 (or 2724 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 21142944 is about 4598.1457132196. The cubic root of 21142944 is about 276.5169894087.

The spelling of 21142944 in words is "twenty-one million, one hundred forty-two thousand, nine hundred forty-four".