21533459 has 2 divisors, whose sum is σ = 21533460. Its totient is φ = 21533458.

The previous prime is 21533443. The next prime is 21533471. The reversal of 21533459 is 95433512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21533459 - 2⁴ = 21533443 is a prime.

It is not a weakly prime, because it can be changed into another prime (21530459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10766729 + 10766730.

It is an arithmetic number, because the mean of its divisors is an integer number (10766730).

Almost surely, 2^21533459 is an apocalyptic number.

21533459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21533459 is an equidigital number, since it uses as much as digits as its factorization.

21533459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 32.

The square root of 21533459 is about 4640.4158218849. The cubic root of 21533459 is about 278.2090581088.

The spelling of 21533459 in words is "twenty-one million, five hundred thirty-three thousand, four hundred fifty-nine".