21099313 has 4 divisors (see below), whose sum is σ = 21779968. Its totient is φ = 20418660.

The previous prime is 21099301. The next prime is 21099371. The reversal of 21099313 is 31399012.

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 a de Polignac number, because none of the positive numbers 2^k-21099313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21099383) 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, 340281 + ... + 340342.

It is an arithmetic number, because the mean of its divisors is an integer number (5444992).

Almost surely, 2^21099313 is an apocalyptic number.

It is an amenable number.

21099313 is a deficient number, since it is larger than the sum of its proper divisors (680655).

21099313 is an equidigital number, since it uses as much as digits as its factorization.

21099313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680654.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 21099313 is about 4593.3988505245. The cubic root of 21099313 is about 276.3266497650.

It can be divided in two parts, 21099 and 313, that added together give a palindrome (21412).

The spelling of 21099313 in words is "twenty-one million, ninety-nine thousand, three hundred thirteen".