21310279 has 2 divisors, whose sum is σ = 21310280. Its totient is φ = 21310278.

The previous prime is 21310271. The next prime is 21310297. The reversal of 21310279 is 97201312.

Together with next prime (21310297) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21310279 - 2³ = 21310271 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21310271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655139 + 10655140.

It is an arithmetic number, because the mean of its divisors is an integer number (10655140).

Almost surely, 2^21310279 is an apocalyptic number.

21310279 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310279 is an equidigital number, since it uses as much as digits as its factorization.

21310279 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 21310279 is about 4616.3057741012. The cubic root of 21310279 is about 277.2445675929.

The spelling of 21310279 in words is "twenty-one million, three hundred ten thousand, two hundred seventy-nine".