21276613 has 2 divisors, whose sum is σ = 21276614. Its totient is φ = 21276612.

The previous prime is 21276611. The next prime is 21276623. The reversal of 21276613 is 31667212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16467364 + 4809249 = 4058^2 + 2193^2 .

It is a cyclic number.

It is not a de Polignac number, because 21276613 - 2¹ = 21276611 is a prime.

Together with 21276611, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21276611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10638306 + 10638307.

It is an arithmetic number, because the mean of its divisors is an integer number (10638307).

Almost surely, 2^21276613 is an apocalyptic number.

It is an amenable number.

21276613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21276613 is an equidigital number, since it uses as much as digits as its factorization.

21276613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 28.

The square root of 21276613 is about 4612.6579105761. The cubic root of 21276613 is about 277.0984935619.

The spelling of 21276613 in words is "twenty-one million, two hundred seventy-six thousand, six hundred thirteen".