21455843 has 2 divisors, whose sum is σ = 21455844. Its totient is φ = 21455842.

The previous prime is 21455821. The next prime is 21455857. The reversal of 21455843 is 34855412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21455843 - 2¹⁴ = 21439459 is a prime.

It is not a weakly prime, because it can be changed into another prime (21455873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10727921 + 10727922.

It is an arithmetic number, because the mean of its divisors is an integer number (10727922).

Almost surely, 2^21455843 is an apocalyptic number.

21455843 is a deficient number, since it is larger than the sum of its proper divisors (1).

21455843 is an equidigital number, since it uses as much as digits as its factorization.

21455843 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19200, while the sum is 32.

The square root of 21455843 is about 4632.0452286220. The cubic root of 21455843 is about 277.8743933369.

The spelling of 21455843 in words is "twenty-one million, four hundred fifty-five thousand, eight hundred forty-three".