21311347 has 2 divisors, whose sum is σ = 21311348. Its totient is φ = 21311346.

The previous prime is 21311261. The next prime is 21311393. The reversal of 21311347 is 74311312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21311347 - 2⁷ = 21311219 is a prime.

It is not a weakly prime, because it can be changed into another prime (21311447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655673 + 10655674.

It is an arithmetic number, because the mean of its divisors is an integer number (10655674).

Almost surely, 2^21311347 is an apocalyptic number.

21311347 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311347 is an equidigital number, since it uses as much as digits as its factorization.

21311347 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 22.

The square root of 21311347 is about 4616.4214495646. The cubic root of 21311347 is about 277.2491990394.

Adding to 21311347 its reverse (74311312), we get a palindrome (95622659).

The spelling of 21311347 in words is "twenty-one million, three hundred eleven thousand, three hundred forty-seven".