21313211 has 4 divisors (see below), whose sum is σ = 21390432. Its totient is φ = 21235992.

The previous prime is 21313207. The next prime is 21313241. The reversal of 21313211 is 11231312.

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

It is a cyclic number.

It is not a de Polignac number, because 21313211 - 2² = 21313207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21313241) 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, 38195 + ... + 38748.

It is an arithmetic number, because the mean of its divisors is an integer number (5347608).

Almost surely, 2^21313211 is an apocalyptic number.

21313211 is a deficient number, since it is larger than the sum of its proper divisors (77221).

21313211 is an equidigital number, since it uses as much as digits as its factorization.

21313211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77220.

The product of its digits is 36, while the sum is 14.

The square root of 21313211 is about 4616.6233331300. The cubic root of 21313211 is about 277.2572820173.

Adding to 21313211 its reverse (11231312), we get a palindrome (32544523).

The spelling of 21313211 in words is "twenty-one million, three hundred thirteen thousand, two hundred eleven".