21784396 has 12 divisors (see below), whose sum is σ = 38379600. Its totient is φ = 10818800.

The previous prime is 21784391. The next prime is 21784403. The reversal of 21784396 is 69348712.

It is not an unprimeable number, because it can be changed into a prime (21784391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17680 + ... + 18871.

It is an arithmetic number, because the mean of its divisors is an integer number (3198300).

Almost surely, 2^21784396 is an apocalyptic number.

It is an amenable number.

21784396 is a deficient number, since it is larger than the sum of its proper divisors (16595204).

21784396 is a wasteful number, since it uses less digits than its factorization.

21784396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36704 (or 36702 counting only the distinct ones).

The product of its digits is 72576, while the sum is 40.

The square root of 21784396 is about 4667.3757080398. The cubic root of 21784396 is about 279.2855766498.

The spelling of 21784396 in words is "twenty-one million, seven hundred eighty-four thousand, three hundred ninety-six".