21010811123 has 2 divisors, whose sum is σ = 21010811124. Its totient is φ = 21010811122.

The previous prime is 21010811119. The next prime is 21010811183. The reversal of 21010811123 is 32111801012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21010811123 - 2² = 21010811119 is a prime.

It is a super-2 number, since 2×21010811123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21010811095 and 21010811104.

It is not a weakly prime, because it can be changed into another prime (21010811183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505405561 + 10505405562.

It is an arithmetic number, because the mean of its divisors is an integer number (10505405562).

Almost surely, 2^21010811123 is an apocalyptic number.

21010811123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010811123 is an equidigital number, since it uses as much as digits as its factorization.

21010811123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 20.

The spelling of 21010811123 in words is "twenty-one billion, ten million, eight hundred eleven thousand, one hundred twenty-three".