20201209981 has 2 divisors, whose sum is σ = 20201209982. Its totient is φ = 20201209980.

The previous prime is 20201209969. The next prime is 20201210033. The reversal of 20201209981 is 18990210202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16065562500 + 4135647481 = 126750^2 + 64309^2 .

It is a cyclic number.

It is not a de Polignac number, because 20201209981 - 2²⁵ = 20167655549 is a prime.

It is a super-2 number, since 2×20201209981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20201209921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10100604990 + 10100604991.

It is an arithmetic number, because the mean of its divisors is an integer number (10100604991).

Almost surely, 2^20201209981 is an apocalyptic number.

It is an amenable number.

20201209981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20201209981 is an equidigital number, since it uses as much as digits as its factorization.

20201209981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The spelling of 20201209981 in words is "twenty billion, two hundred one million, two hundred nine thousand, nine hundred eighty-one".