21523873 has 8 divisors (see below), whose sum is σ = 24651648. Its totient is φ = 18409344.

The previous prime is 21523847. The next prime is 21523891. The reversal of 21523873 is 37832512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21523873 - 2⁹ = 21523361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21523813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 465 + ... + 6577.

It is an arithmetic number, because the mean of its divisors is an integer number (3081456).

Almost surely, 2^21523873 is an apocalyptic number.

It is an amenable number.

21523873 is a deficient number, since it is larger than the sum of its proper divisors (3127775).

21523873 is an equidigital number, since it uses as much as digits as its factorization.

21523873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6623.

The product of its digits is 10080, while the sum is 31.

The square root of 21523873 is about 4639.3828253336. The cubic root of 21523873 is about 278.1677687543.

The spelling of 21523873 in words is "twenty-one million, five hundred twenty-three thousand, eight hundred seventy-three".