21302123 has 2 divisors, whose sum is σ = 21302124. Its totient is φ = 21302122.

The previous prime is 21302111. The next prime is 21302129. The reversal of 21302123 is 32120312.

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-21302123 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21302098 and 21302107.

It is not a weakly prime, because it can be changed into another prime (21302129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651061 + 10651062.

It is an arithmetic number, because the mean of its divisors is an integer number (10651062).

Almost surely, 2^21302123 is an apocalyptic number.

21302123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302123 is an equidigital number, since it uses as much as digits as its factorization.

21302123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21302123 is about 4615.4222992051. The cubic root of 21302123 is about 277.2091935022.

Adding to 21302123 its reverse (32120312), we get a palindrome (53422435).

The spelling of 21302123 in words is "twenty-one million, three hundred two thousand, one hundred twenty-three".