21784130 has 16 divisors (see below), whose sum is σ = 39579840. Its totient is φ = 8631792.

The previous prime is 21784129. The next prime is 21784177. The reversal of 21784130 is 3148712.

It is a self number, because there is not a number n which added to its sum of digits gives 21784130.

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, 9110 + ... + 11249.

It is an arithmetic number, because the mean of its divisors is an integer number (2473740).

Almost surely, 2^21784130 is an apocalyptic number.

21784130 is a deficient number, since it is larger than the sum of its proper divisors (17795710).

21784130 is a wasteful number, since it uses less digits than its factorization.

21784130 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20473.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21784130 is about 4667.3472122824. The cubic root of 21784130 is about 279.2844398994.

The spelling of 21784130 in words is "twenty-one million, seven hundred eighty-four thousand, one hundred thirty".