21312573 has 8 divisors (see below), whose sum is σ = 29021568. Its totient is φ = 13905984.

The previous prime is 21312539. The next prime is 21312587. The reversal of 21312573 is 37521312.

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

It is not a de Polignac number, because 21312573 - 2¹² = 21308477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75436 + ... + 75717.

It is an arithmetic number, because the mean of its divisors is an integer number (3627696).

Almost surely, 2^21312573 is an apocalyptic number.

It is an amenable number.

21312573 is a deficient number, since it is larger than the sum of its proper divisors (7708995).

21312573 is a wasteful number, since it uses less digits than its factorization.

21312573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151203.

The product of its digits is 1260, while the sum is 24.

The square root of 21312573 is about 4616.5542344913. The cubic root of 21312573 is about 277.2545154717.

Adding to 21312573 its reverse (37521312), we get a palindrome (58833885).

The spelling of 21312573 in words is "twenty-one million, three hundred twelve thousand, five hundred seventy-three".