21278363 has 2 divisors, whose sum is σ = 21278364. Its totient is φ = 21278362.

The previous prime is 21278317. The next prime is 21278393. The reversal of 21278363 is 36387212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21278363 - 2¹⁰ = 21277339 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21278393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10639181 + 10639182.

It is an arithmetic number, because the mean of its divisors is an integer number (10639182).

Almost surely, 2^21278363 is an apocalyptic number.

21278363 is a deficient number, since it is larger than the sum of its proper divisors (1).

21278363 is an equidigital number, since it uses as much as digits as its factorization.

21278363 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 32.

The square root of 21278363 is about 4612.8476020784. The cubic root of 21278363 is about 277.1060904645.

The spelling of 21278363 in words is "twenty-one million, two hundred seventy-eight thousand, three hundred sixty-three".