21864959 has 2 divisors, whose sum is σ = 21864960. Its totient is φ = 21864958.

The previous prime is 21864923. The next prime is 21864989. The reversal of 21864959 is 95946812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21864959 - 2¹² = 21860863 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21864989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10932479 + 10932480.

It is an arithmetic number, because the mean of its divisors is an integer number (10932480).

Almost surely, 2^21864959 is an apocalyptic number.

21864959 is a deficient number, since it is larger than the sum of its proper divisors (1).

21864959 is an equidigital number, since it uses as much as digits as its factorization.

21864959 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 44.

The square root of 21864959 is about 4675.9981822067. The cubic root of 21864959 is about 279.6294375212.

The spelling of 21864959 in words is "twenty-one million, eight hundred sixty-four thousand, nine hundred fifty-nine".