21867823 has 2 divisors, whose sum is σ = 21867824. Its totient is φ = 21867822.

The previous prime is 21867821. The next prime is 21867869. The reversal of 21867823 is 32876812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21867823 - 2¹ = 21867821 is a prime.

Together with 21867821, 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 (21867821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10933911 + 10933912.

It is an arithmetic number, because the mean of its divisors is an integer number (10933912).

Almost surely, 2^21867823 is an apocalyptic number.

21867823 is a deficient number, since it is larger than the sum of its proper divisors (1).

21867823 is an equidigital number, since it uses as much as digits as its factorization.

21867823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 37.

The square root of 21867823 is about 4676.3044169515. The cubic root of 21867823 is about 279.6416461536.

The spelling of 21867823 in words is "twenty-one million, eight hundred sixty-seven thousand, eight hundred twenty-three".