21250123 has 2 divisors, whose sum is σ = 21250124. Its totient is φ = 21250122.

The previous prime is 21250121. The next prime is 21250129. The reversal of 21250123 is 32105212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21250123 - 2¹ = 21250121 is a prime.

Together with 21250121, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21250097 and 21250106.

It is not a weakly prime, because it can be changed into another prime (21250121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625061 + 10625062.

It is an arithmetic number, because the mean of its divisors is an integer number (10625062).

Almost surely, 2^21250123 is an apocalyptic number.

21250123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21250123 is an equidigital number, since it uses as much as digits as its factorization.

21250123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21250123 is about 4609.7855698503. The cubic root of 21250123 is about 276.9834472508.

Adding to 21250123 its reverse (32105212), we get a palindrome (53355335).

The spelling of 21250123 in words is "twenty-one million, two hundred fifty thousand, one hundred twenty-three".