21312853 has 4 divisors (see below), whose sum is σ = 21325248. Its totient is φ = 21300460.

The previous prime is 21312833. The next prime is 21312871. The reversal of 21312853 is 35821312.

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 21312853 - 2⁹ = 21312341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312833) 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, 3103 + ... + 7228.

It is an arithmetic number, because the mean of its divisors is an integer number (5331312).

Almost surely, 2^21312853 is an apocalyptic number.

It is an amenable number.

21312853 is a deficient number, since it is larger than the sum of its proper divisors (12395).

21312853 is a wasteful number, since it uses less digits than its factorization.

21312853 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12394.

The product of its digits is 1440, while the sum is 25.

The square root of 21312853 is about 4616.5845600400. The cubic root of 21312853 is about 277.2557296365.

The spelling of 21312853 in words is "twenty-one million, three hundred twelve thousand, eight hundred fifty-three".