21784868 has 24 divisors (see below), whose sum is σ = 45864000. Its totient is φ = 8844768.

The previous prime is 21784853. The next prime is 21784883. The reversal of 21784868 is 86848712.

It is an interprime number because it is at equal distance from previous prime (21784853) and next prime (21784883).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19943 + ... + 21006.

It is an arithmetic number, because the mean of its divisors is an integer number (1911000).

Almost surely, 2^21784868 is an apocalyptic number.

21784868 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21784868 is an abundant number, since it is smaller than the sum of its proper divisors (24079132).

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

21784868 is a wasteful number, since it uses less digits than its factorization.

21784868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40979 (or 40977 counting only the distinct ones).

The product of its digits is 172032, while the sum is 44.

The square root of 21784868 is about 4667.4262715120. The cubic root of 21784868 is about 279.2875937181.

The spelling of 21784868 in words is "twenty-one million, seven hundred eighty-four thousand, eight hundred sixty-eight".