21311313 has 4 divisors (see below), whose sum is σ = 28415088. Its totient is φ = 14207540.

The previous prime is 21311261. The next prime is 21311347. The reversal of 21311313 is 31311312.

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 21311313 - 2⁶ = 21311249 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21311292 and 21311301.

It is not an unprimeable number, because it can be changed into a prime (21311393) 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, 3551883 + ... + 3551888.

It is an arithmetic number, because the mean of its divisors is an integer number (7103772).

Almost surely, 2^21311313 is an apocalyptic number.

It is an amenable number.

21311313 is a deficient number, since it is larger than the sum of its proper divisors (7103775).

21311313 is an equidigital number, since it uses as much as digits as its factorization.

21311313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7103774.

The product of its digits is 54, while the sum is 15.

The square root of 21311313 is about 4616.4177670571. The cubic root of 21311313 is about 277.2490515988.

Adding to 21311313 its reverse (31311312), we get a palindrome (52622625).

Subtracting 21311313 from its reverse (31311312), we obtain a palindrome (9999999).

The spelling of 21311313 in words is "twenty-one million, three hundred eleven thousand, three hundred thirteen".