21289473 has 24 divisors (see below), whose sum is σ = 32323200. Its totient is φ = 14000688.

The previous prime is 21289459. The next prime is 21289493. The reversal of 21289473 is 37498212.

It is not a de Polignac number, because 21289473 - 2⁶ = 21289409 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21289453) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18643 + ... + 19751.

It is an arithmetic number, because the mean of its divisors is an integer number (1346800).

Almost surely, 2^21289473 is an apocalyptic number.

It is an amenable number.

21289473 is a deficient number, since it is larger than the sum of its proper divisors (11033727).

21289473 is an equidigital number, since it uses as much as digits as its factorization.

21289473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1203 (or 1191 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21289473 is about 4614.0516902176. The cubic root of 21289473 is about 277.1543102297.

The spelling of 21289473 in words is "twenty-one million, two hundred eighty-nine thousand, four hundred seventy-three".