21263873 has 4 divisors (see below), whose sum is σ = 21997140. Its totient is φ = 20530608.

The previous prime is 21263867. The next prime is 21263897. The reversal of 21263873 is 37836212.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7772944 + 13490929 = 2788^2 + 3673^2 .

It is not a de Polignac number, because 21263873 - 2¹⁰ = 21262849 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21263173) 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, 366590 + ... + 366647.

It is an arithmetic number, because the mean of its divisors is an integer number (5499285).

Almost surely, 2^21263873 is an apocalyptic number.

It is an amenable number.

21263873 is a deficient number, since it is larger than the sum of its proper divisors (733267).

21263873 is an equidigital number, since it uses as much as digits as its factorization.

21263873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733266.

The product of its digits is 12096, while the sum is 32.

The square root of 21263873 is about 4611.2767212563. The cubic root of 21263873 is about 277.0431755522.

The spelling of 21263873 in words is "twenty-one million, two hundred sixty-three thousand, eight hundred seventy-three".