21239459 has 2 divisors, whose sum is σ = 21239460. Its totient is φ = 21239458.

The previous prime is 21239453. The next prime is 21239461. The reversal of 21239459 is 95493212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21239459 - 2⁸ = 21239203 is a prime.

It is a super-2 number, since 2×21239459² = 902229237225362, which contains 22 as substring.

Together with 21239461, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21239453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10619729 + 10619730.

It is an arithmetic number, because the mean of its divisors is an integer number (10619730).

Almost surely, 2^21239459 is an apocalyptic number.

21239459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21239459 is an equidigital number, since it uses as much as digits as its factorization.

21239459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 35.

The square root of 21239459 is about 4608.6287548467. The cubic root of 21239459 is about 276.9371064098.

The spelling of 21239459 in words is "twenty-one million, two hundred thirty-nine thousand, four hundred fifty-nine".