21242984 has 32 divisors (see below), whose sum is σ = 47502720. Its totient is φ = 8707776.

The previous prime is 21242981. The next prime is 21242999. The reversal of 21242984 is 48924212.

21242984 = 32² + 33² + ... + 399².

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21242984.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242981) 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, 6959 + ... + 9534.

It is an arithmetic number, because the mean of its divisors is an integer number (1484460).

Almost surely, 2^21242984 is an apocalyptic number.

It is an amenable number.

21242984 is an abundant number, since it is smaller than the sum of its proper divisors (26259736).

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

21242984 is a wasteful number, since it uses less digits than its factorization.

21242984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16529 (or 16525 counting only the distinct ones).

The product of its digits is 9216, while the sum is 32.

The square root of 21242984 is about 4609.0111737769. The cubic root of 21242984 is about 276.9524261550.

The spelling of 21242984 in words is "twenty-one million, two hundred forty-two thousand, nine hundred eighty-four".