21242816 has 28 divisors (see below), whose sum is σ = 48176688. Its totient is φ = 9103872.

The previous prime is 21242807. The next prime is 21242821. The reversal of 21242816 is 61824212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23261 + ... + 24156.

It is an arithmetic number, because the mean of its divisors is an integer number (1720596).

Almost surely, 2^21242816 is an apocalyptic number.

It is an amenable number.

21242816 is an abundant number, since it is smaller than the sum of its proper divisors (26933872).

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

21242816 is an equidigital number, since it uses as much as digits as its factorization.

21242816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47436 (or 47426 counting only the distinct ones).

The product of its digits is 1536, while the sum is 26.

The square root of 21242816 is about 4608.9929485735. The cubic root of 21242816 is about 276.9516960609.

The spelling of 21242816 in words is "twenty-one million, two hundred forty-two thousand, eight hundred sixteen".