21201311123 has 2 divisors, whose sum is σ = 21201311124. Its totient is φ = 21201311122.

The previous prime is 21201311119. The next prime is 21201311179. The reversal of 21201311123 is 32111310212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21201311123 - 2² = 21201311119 is a prime.

It is a super-2 number, since 2×21201311123² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21201311113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600655561 + 10600655562.

It is an arithmetic number, because the mean of its divisors is an integer number (10600655562).

Almost surely, 2^21201311123 is an apocalyptic number.

21201311123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201311123 is an equidigital number, since it uses as much as digits as its factorization.

21201311123 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 17.

Adding to 21201311123 its reverse (32111310212), we get a palindrome (53312621335).

The spelling of 21201311123 in words is "twenty-one billion, two hundred one million, three hundred eleven thousand, one hundred twenty-three".