21073813 has 4 divisors (see below), whose sum is σ = 21522240. Its totient is φ = 20625388.

The previous prime is 21073799. The next prime is 21073837. The reversal of 21073813 is 31837012.

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 21073813 - 2⁹ = 21073301 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21073873) 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, 224143 + ... + 224236.

It is an arithmetic number, because the mean of its divisors is an integer number (5380560).

Almost surely, 2^21073813 is an apocalyptic number.

It is an amenable number.

21073813 is a deficient number, since it is larger than the sum of its proper divisors (448427).

21073813 is an equidigital number, since it uses as much as digits as its factorization.

21073813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448426.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21073813 is about 4590.6222889713. The cubic root of 21073813 is about 276.2152848414.

The spelling of 21073813 in words is "twenty-one million, seventy-three thousand, eight hundred thirteen".