21213131123 has 2 divisors, whose sum is σ = 21213131124. Its totient is φ = 21213131122.

The previous prime is 21213131083. The next prime is 21213131141. The reversal of 21213131123 is 32113131212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21213131123 - 2²⁴ = 21196353907 is a prime.

It is a super-2 number, since 2×21213131123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21213131095 and 21213131104.

It is not a weakly prime, because it can be changed into another prime (21213121123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606565561 + 10606565562.

It is an arithmetic number, because the mean of its divisors is an integer number (10606565562).

Almost surely, 2^21213131123 is an apocalyptic number.

21213131123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213131123 is an equidigital number, since it uses as much as digits as its factorization.

21213131123 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 20.

Adding to 21213131123 its reverse (32113131212), we get a palindrome (53326262335).

The spelling of 21213131123 in words is "twenty-one billion, two hundred thirteen million, one hundred thirty-one thousand, one hundred twenty-three".