21573863 has 2 divisors, whose sum is σ = 21573864. Its totient is φ = 21573862.

The previous prime is 21573857. The next prime is 21573887. The reversal of 21573863 is 36837512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21573863 - 2²⁰ = 20525287 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21573803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786931 + 10786932.

It is an arithmetic number, because the mean of its divisors is an integer number (10786932).

Almost surely, 2^21573863 is an apocalyptic number.

21573863 is a deficient number, since it is larger than the sum of its proper divisors (1).

21573863 is an equidigital number, since it uses as much as digits as its factorization.

21573863 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 35.

The square root of 21573863 is about 4644.7672708113. The cubic root of 21573863 is about 278.3829539303.

The spelling of 21573863 in words is "twenty-one million, five hundred seventy-three thousand, eight hundred sixty-three".