21456023 has 4 divisors (see below), whose sum is σ = 22718160. Its totient is φ = 20193888.

The previous prime is 21456007. The next prime is 21456047. The reversal of 21456023 is 32065412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21456023 - 2⁴ = 21456007 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21456023.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 631043 + ... + 631076.

It is an arithmetic number, because the mean of its divisors is an integer number (5679540).

Almost surely, 2^21456023 is an apocalyptic number.

21456023 is a deficient number, since it is larger than the sum of its proper divisors (1262137).

21456023 is a wasteful number, since it uses less digits than its factorization.

21456023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1262136.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21456023 is about 4632.0646584434. The cubic root of 21456023 is about 277.8751703940.

The spelling of 21456023 in words is "twenty-one million, four hundred fifty-six thousand, twenty-three".