21259123 has 2 divisors, whose sum is σ = 21259124. Its totient is φ = 21259122.

The previous prime is 21259103. The next prime is 21259141. The reversal of 21259123 is 32195212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21259123 is a prime.

It is not a weakly prime, because it can be changed into another prime (21259103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10629561 + 10629562.

It is an arithmetic number, because the mean of its divisors is an integer number (10629562).

Almost surely, 2^21259123 is an apocalyptic number.

21259123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21259123 is an equidigital number, since it uses as much as digits as its factorization.

21259123 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1080, while the sum is 25.

The square root of 21259123 is about 4610.7616507471. The cubic root of 21259123 is about 277.0225450508.

It can be divided in two parts, 2125912 and 3, that multiplied together give a palindrome (6377736).

The spelling of 21259123 in words is "twenty-one million, two hundred fifty-nine thousand, one hundred twenty-three".