21813353 has 4 divisors (see below), whose sum is σ = 22345428. Its totient is φ = 21281280.

The previous prime is 21813343. The next prime is 21813371. The reversal of 21813353 is 35331812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3810304 + 18003049 = 1952^2 + 4243^2 .

It is a cyclic number.

It is not a de Polignac number, because 21813353 - 2⁶ = 21813289 is a prime.

It is a Duffinian number.

It is a Curzon number.

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 3 ways as a sum of consecutive naturals, for example, 265976 + ... + 266057.

It is an arithmetic number, because the mean of its divisors is an integer number (5586357).

Almost surely, 2^21813353 is an apocalyptic number.

It is an amenable number.

21813353 is a deficient number, since it is larger than the sum of its proper divisors (532075).

21813353 is an equidigital number, since it uses as much as digits as its factorization.

21813353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 532074.

The product of its digits is 2160, while the sum is 26.

The square root of 21813353 is about 4670.4767422609. The cubic root of 21813353 is about 279.4092690356.

The spelling of 21813353 in words is "twenty-one million, eight hundred thirteen thousand, three hundred fifty-three".