21813313 has 8 divisors (see below), whose sum is σ = 22675968. Its totient is φ = 20965104.

The previous prime is 21813301. The next prime is 21813331. The reversal of 21813313 is 31331812.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21813313 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21813343) 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, 481 + ... + 6622.

It is an arithmetic number, because the mean of its divisors is an integer number (2834496).

Almost surely, 2^21813313 is an apocalyptic number.

It is an amenable number.

21813313 is a deficient number, since it is larger than the sum of its proper divisors (862655).

21813313 is an equidigital number, since it uses as much as digits as its factorization.

21813313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7223.

The product of its digits is 432, while the sum is 22.

The square root of 21813313 is about 4670.4724600408. The cubic root of 21813313 is about 279.4090982475.

It can be divided in two parts, 218 and 13313, that added together give a palindrome (13531).

The spelling of 21813313 in words is "twenty-one million, eight hundred thirteen thousand, three hundred thirteen".