21258473 has 4 divisors (see below), whose sum is σ = 22377360. Its totient is φ = 20139588.

The previous prime is 21258443. The next prime is 21258481. The reversal of 21258473 is 37485212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21258473 - 2¹² = 21254377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21258443) 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, 559415 + ... + 559452.

It is an arithmetic number, because the mean of its divisors is an integer number (5594340).

Almost surely, 2^21258473 is an apocalyptic number.

It is an amenable number.

21258473 is a deficient number, since it is larger than the sum of its proper divisors (1118887).

21258473 is a wasteful number, since it uses less digits than its factorization.

21258473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1118886.

The product of its digits is 13440, while the sum is 32.

The square root of 21258473 is about 4610.6911629386. The cubic root of 21258473 is about 277.0197216905.

It can be divided in two parts, 212 and 58473, that added together give a palindrome (58685).

The spelling of 21258473 in words is "twenty-one million, two hundred fifty-eight thousand, four hundred seventy-three".