21331220123 has 2 divisors, whose sum is σ = 21331220124. Its totient is φ = 21331220122.

The previous prime is 21331220089. The next prime is 21331220147. The reversal of 21331220123 is 32102213312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21331220123 - 2²⁸ = 21062784667 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21331220095 and 21331220104.

It is not a weakly prime, because it can be changed into another prime (21331226123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10665610061 + 10665610062.

It is an arithmetic number, because the mean of its divisors is an integer number (10665610062).

Almost surely, 2^21331220123 is an apocalyptic number.

21331220123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331220123 is an equidigital number, since it uses as much as digits as its factorization.

21331220123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21331220123 its reverse (32102213312), we get a palindrome (53433433435).

The spelling of 21331220123 in words is "twenty-one billion, three hundred thirty-one million, two hundred twenty thousand, one hundred twenty-three".