21456824 has 8 divisors (see below), whose sum is σ = 40231560. Its totient is φ = 10728408.

The previous prime is 21456797. The next prime is 21456829. The reversal of 21456824 is 42865412.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1341044 + ... + 1341059.

It is an arithmetic number, because the mean of its divisors is an integer number (5028945).

Almost surely, 2^21456824 is an apocalyptic number.

It is an amenable number.

21456824 is a deficient number, since it is larger than the sum of its proper divisors (18774736).

21456824 is a wasteful number, since it uses less digits than its factorization.

21456824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2682109 (or 2682105 counting only the distinct ones).

The product of its digits is 15360, while the sum is 32.

The square root of 21456824 is about 4632.1511201600. The cubic root of 21456824 is about 277.8786282458.

The spelling of 21456824 in words is "twenty-one million, four hundred fifty-six thousand, eight hundred twenty-four".