21122132981 has 2 divisors, whose sum is σ = 21122132982. Its totient is φ = 21122132980.

The previous prime is 21122132959. The next prime is 21122133023. The reversal of 21122132981 is 18923122112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14273080900 + 6849052081 = 119470^2 + 82759^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122132981 - 2¹⁸ = 21121870837 is a prime.

It is a super-2 number, since 2×21122132981² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21122132081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561066490 + 10561066491.

It is an arithmetic number, because the mean of its divisors is an integer number (10561066491).

Almost surely, 2^21122132981 is an apocalyptic number.

It is an amenable number.

21122132981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122132981 is an equidigital number, since it uses as much as digits as its factorization.

21122132981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 32.

The spelling of 21122132981 in words is "twenty-one billion, one hundred twenty-two million, one hundred thirty-two thousand, nine hundred eighty-one".