21235999 has 2 divisors, whose sum is σ = 21236000. Its totient is φ = 21235998.

The previous prime is 21235997. The next prime is 21236021. The reversal of 21235999 is 99953212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21235999 - 2¹ = 21235997 is a prime.

Together with 21235997, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21235993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10617999 + 10618000.

It is an arithmetic number, because the mean of its divisors is an integer number (10618000).

Almost surely, 2^21235999 is an apocalyptic number.

21235999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21235999 is an equidigital number, since it uses as much as digits as its factorization.

21235999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43740, while the sum is 40.

The square root of 21235999 is about 4608.2533567503. The cubic root of 21235999 is about 276.9220675078.

The spelling of 21235999 in words is "twenty-one million, two hundred thirty-five thousand, nine hundred ninety-nine".