21123332081 has 2 divisors, whose sum is σ = 21123332082. Its totient is φ = 21123332080.

The previous prime is 21123332077. The next prime is 21123332101. The reversal of 21123332081 is 18023332112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19194717025 + 1928615056 = 138545^2 + 43916^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123332081 - 2² = 21123332077 is a prime.

It is a super-2 number, since 2×21123332081² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21123332081.

It is not a weakly prime, because it can be changed into another prime (21123332051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561666040 + 10561666041.

It is an arithmetic number, because the mean of its divisors is an integer number (10561666041).

Almost surely, 2^21123332081 is an apocalyptic number.

It is an amenable number.

21123332081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123332081 is an equidigital number, since it uses as much as digits as its factorization.

21123332081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 26.

Adding to 21123332081 its reverse (18023332112), we get a palindrome (39146664193).

The spelling of 21123332081 in words is "twenty-one billion, one hundred twenty-three million, three hundred thirty-two thousand, eighty-one".