21267823 has 2 divisors, whose sum is σ = 21267824. Its totient is φ = 21267822.

The previous prime is 21267803. The next prime is 21267839. The reversal of 21267823 is 32876212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21267823 - 2⁵ = 21267791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21267803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10633911 + 10633912.

It is an arithmetic number, because the mean of its divisors is an integer number (10633912).

Almost surely, 2^21267823 is an apocalyptic number.

21267823 is a deficient number, since it is larger than the sum of its proper divisors (1).

21267823 is an equidigital number, since it uses as much as digits as its factorization.

21267823 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 31.

The square root of 21267823 is about 4611.7049992384. The cubic root of 21267823 is about 277.0603291032.

The spelling of 21267823 in words is "twenty-one million, two hundred sixty-seven thousand, eight hundred twenty-three".