21310297 has 2 divisors, whose sum is σ = 21310298. Its totient is φ = 21310296.

The previous prime is 21310279. The next prime is 21310301. The reversal of 21310297 is 79201312.

Together with previous prime (21310279) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18156121 + 3154176 = 4261^2 + 1776^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21310297 is a prime.

It is not a weakly prime, because it can be changed into another prime (21310207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655148 + 10655149.

It is an arithmetic number, because the mean of its divisors is an integer number (10655149).

Almost surely, 2^21310297 is an apocalyptic number.

It is an amenable number.

21310297 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310297 is an equidigital number, since it uses as much as digits as its factorization.

21310297 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21310297 is about 4616.3077237117. The cubic root of 21310297 is about 277.2446456523.

The spelling of 21310297 in words is "twenty-one million, three hundred ten thousand, two hundred ninety-seven".