21893040 has 120 divisors (see below), whose sum is σ = 79213680. Its totient is φ = 5386752.

The previous prime is 21893009. The next prime is 21893051. The reversal of 21893040 is 4039812.

It is a Cunningham number, because it is equal to 4679²-1.

It is a tau number, because it is divible by the number of its divisors (120).

It is a junction number, because it is equal to n+sod(n) for n = 21892995 and 21893013.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8191 + ... + 10529.

It is an arithmetic number, because the mean of its divisors is an integer number (660114).

Almost surely, 2^21893040 is an apocalyptic number.

21893040 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 21893040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39606840).

21893040 is an abundant number, since it is smaller than the sum of its proper divisors (57320640).

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

21893040 is a wasteful number, since it uses less digits than its factorization.

21893040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2371 (or 2362 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21893040 is about 4678.9998931396. Note that the first 3 decimals coincide. The cubic root of 21893040 is about 279.7490949617.

The spelling of 21893040 in words is "twenty-one million, eight hundred ninety-three thousand, forty".