21250640123 has 2 divisors, whose sum is σ = 21250640124. Its totient is φ = 21250640122.

The previous prime is 21250640071. The next prime is 21250640129. The reversal of 21250640123 is 32104605212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21250640123 - 2⁸ = 21250639867 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21250640092 and 21250640101.

It is not a weakly prime, because it can be changed into another prime (21250640129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625320061 + 10625320062.

It is an arithmetic number, because the mean of its divisors is an integer number (10625320062).

Almost surely, 2^21250640123 is an apocalyptic number.

21250640123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21250640123 is an equidigital number, since it uses as much as digits as its factorization.

21250640123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 26.

The spelling of 21250640123 in words is "twenty-one billion, two hundred fifty million, six hundred forty thousand, one hundred twenty-three".