21288023 has 2 divisors, whose sum is σ = 21288024. Its totient is φ = 21288022.

The previous prime is 21288013. The next prime is 21288031. The reversal of 21288023 is 32088212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21288023 - 2⁸ = 21287767 is a prime.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 21287983 and 21288001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21288013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10644011 + 10644012.

It is an arithmetic number, because the mean of its divisors is an integer number (10644012).

Almost surely, 2^21288023 is an apocalyptic number.

21288023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21288023 is an equidigital number, since it uses as much as digits as its factorization.

21288023 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21288023 is about 4613.8945588299. The cubic root of 21288023 is about 277.1480178730.

The spelling of 21288023 in words is "twenty-one million, two hundred eighty-eight thousand, twenty-three".