20121220981 has 2 divisors, whose sum is σ = 20121220982. Its totient is φ = 20121220980.

The previous prime is 20121220979. The next prime is 20121221033. The reversal of 20121220981 is 18902212102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19934898481 + 186322500 = 141191^2 + 13650^2 .

It is a cyclic number.

It is not a de Polignac number, because 20121220981 - 2¹ = 20121220979 is a prime.

It is a super-2 number, since 2×20121220981² (a number of 21 digits) contains 22 as substring.

Together with 20121220979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20121220181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060610490 + 10060610491.

It is an arithmetic number, because the mean of its divisors is an integer number (10060610491).

Almost surely, 2^20121220981 is an apocalyptic number.

It is an amenable number.

20121220981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121220981 is an equidigital number, since it uses as much as digits as its factorization.

20121220981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 28.

The spelling of 20121220981 in words is "twenty billion, one hundred twenty-one million, two hundred twenty thousand, nine hundred eighty-one".