21816456 has 16 divisors (see below), whose sum is σ = 54541200. Its totient is φ = 7272144.

The previous prime is 21816451. The next prime is 21816463. The reversal of 21816456 is 65461812.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21816451) 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, 454486 + ... + 454533.

It is an arithmetic number, because the mean of its divisors is an integer number (3408825).

Almost surely, 2^21816456 is an apocalyptic number.

It is an amenable number.

21816456 is an abundant number, since it is smaller than the sum of its proper divisors (32724744).

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

21816456 is a wasteful number, since it uses less digits than its factorization.

21816456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909028 (or 909024 counting only the distinct ones).

The product of its digits is 11520, while the sum is 33.

The square root of 21816456 is about 4670.8089235164. The cubic root of 21816456 is about 279.4225172793.

The spelling of 21816456 in words is "twenty-one million, eight hundred sixteen thousand, four hundred fifty-six".