21874840 has 128 divisors (see below), whose sum is σ = 58060800. Its totient is φ = 7349760.

The previous prime is 21874837. The next prime is 21874843. The reversal of 21874840 is 4847812.

It is an interprime number because it is at equal distance from previous prime (21874837) and next prime (21874843).

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21874796 and 21874805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21874843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 370731 + ... + 370789.

It is an arithmetic number, because the mean of its divisors is an integer number (453600).

Almost surely, 2^21874840 is an apocalyptic number.

21874840 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 21874840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29030400).

21874840 is an abundant number, since it is smaller than the sum of its proper divisors (36185960).

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

21874840 is a wasteful number, since it uses less digits than its factorization.

21874840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 14336, while the sum is 34.

The square root of 21874840 is about 4677.0546287167. The cubic root of 21874840 is about 279.6715536511.

The spelling of 21874840 in words is "twenty-one million, eight hundred seventy-four thousand, eight hundred forty".