21102020123 has 2 divisors, whose sum is σ = 21102020124. Its totient is φ = 21102020122.

The previous prime is 21102020101. The next prime is 21102020161. The reversal of 21102020123 is 32102020112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21102020123 - 2⁸ = 21102019867 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21102020098 and 21102020107.

It is not a weakly prime, because it can be changed into another prime (21102020183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551010061 + 10551010062.

It is an arithmetic number, because the mean of its divisors is an integer number (10551010062).

Almost surely, 2^21102020123 is an apocalyptic number.

21102020123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102020123 is an equidigital number, since it uses as much as digits as its factorization.

21102020123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21102020123 its reverse (32102020112), we get a palindrome (53204040235).

The spelling of 21102020123 in words is "twenty-one billion, one hundred two million, twenty thousand, one hundred twenty-three".