21956863 has 2 divisors, whose sum is σ = 21956864. Its totient is φ = 21956862.

The previous prime is 21956861. The next prime is 21956887. The reversal of 21956863 is 36865912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21956863 - 2¹ = 21956861 is a prime.

Together with 21956861, 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 (21956861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978431 + 10978432.

It is an arithmetic number, because the mean of its divisors is an integer number (10978432).

Almost surely, 2^21956863 is an apocalyptic number.

21956863 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956863 is an equidigital number, since it uses as much as digits as its factorization.

21956863 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 40.

The square root of 21956863 is about 4685.8150838461. The cubic root of 21956863 is about 280.0206744938.

The spelling of 21956863 in words is "twenty-one million, nine hundred fifty-six thousand, eight hundred sixty-three".