21859447 has 2 divisors, whose sum is σ = 21859448. Its totient is φ = 21859446.

The previous prime is 21859429. The next prime is 21859451. The reversal of 21859447 is 74495812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21859447 - 2²³ = 13470839 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 (21859427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10929723 + 10929724.

It is an arithmetic number, because the mean of its divisors is an integer number (10929724).

Almost surely, 2^21859447 is an apocalyptic number.

21859447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21859447 is an equidigital number, since it uses as much as digits as its factorization.

21859447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 40.

The square root of 21859447 is about 4675.4087521841. The cubic root of 21859447 is about 279.6059380184.

The spelling of 21859447 in words is "twenty-one million, eight hundred fifty-nine thousand, four hundred forty-seven".