21889440 has 144 divisors (see below), whose sum is σ = 77601888. Its totient is φ = 5826816.

The previous prime is 21889429. The next prime is 21889447. The reversal of 21889440 is 4498812.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21889395 and 21889404.

It is not an unprimeable number, because it can be changed into a prime (21889447) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38599 + ... + 39161.

It is an arithmetic number, because the mean of its divisors is an integer number (538902).

Almost surely, 2^21889440 is an apocalyptic number.

21889440 is a gapful number since it is divisible by the number (20) 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 21889440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38800944).

21889440 is an abundant number, since it is smaller than the sum of its proper divisors (55712448).

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

21889440 is an equidigital number, since it uses as much as digits as its factorization.

21889440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 593 (or 573 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 21889440 is about 4678.6151797300. The cubic root of 21889440 is about 279.7337605305.

It can be divided in two parts, 2188 and 9440, that added together give a triangular number (11628 = T₁₅₂).

The spelling of 21889440 in words is "twenty-one million, eight hundred eighty-nine thousand, four hundred forty".