21874240 has 56 divisors (see below), whose sum is σ = 55165752. Its totient is φ = 8232960.

The previous prime is 21874199. The next prime is 21874241. The reversal of 21874240 is 4247812.

It can be written as a sum of positive squares in 4 ways, for example, as 861184 + 21013056 = 928^2 + 4584^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21874199 and 21874208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21874241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3430 + ... + 7450.

Almost surely, 2^21874240 is an apocalyptic number.

21874240 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 21874240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27582876).

21874240 is an abundant number, since it is smaller than the sum of its proper divisors (33291512).

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

21874240 is a wasteful number, since it uses less digits than its factorization.

21874240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4055 (or 4045 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 21874240 is about 4676.9904853442. The cubic root of 21874240 is about 279.6689966120.

The spelling of 21874240 in words is "twenty-one million, eight hundred seventy-four thousand, two hundred forty".