21805967 has 2 divisors, whose sum is σ = 21805968. Its totient is φ = 21805966.

The previous prime is 21805963. The next prime is 21805981. The reversal of 21805967 is 76950812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21805967 - 2² = 21805963 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21805967.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21805963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10902983 + 10902984.

It is an arithmetic number, because the mean of its divisors is an integer number (10902984).

Almost surely, 2^21805967 is an apocalyptic number.

21805967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21805967 is an equidigital number, since it uses as much as digits as its factorization.

21805967 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21805967 is about 4669.6859637453. The cubic root of 21805967 is about 279.3777294884.

The spelling of 21805967 in words is "twenty-one million, eight hundred five thousand, nine hundred sixty-seven".