202111981 has 2 divisors, whose sum is σ = 202111982. Its totient is φ = 202111980.

The previous prime is 202111967. The next prime is 202112003. The reversal of 202111981 is 189111202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 122456356 + 79655625 = 11066^2 + 8925^2 .

It is a cyclic number.

It is not a de Polignac number, because 202111981 - 2¹³ = 202103789 is a prime.

It is a super-2 number, since 2×202111981² = 81698505727488722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (202111901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 101055990 + 101055991.

It is an arithmetic number, because the mean of its divisors is an integer number (101055991).

Almost surely, 2^202111981 is an apocalyptic number.

It is an amenable number.

202111981 is a deficient number, since it is larger than the sum of its proper divisors (1).

202111981 is an equidigital number, since it uses as much as digits as its factorization.

202111981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 25.

The square root of 202111981 is about 14216.6093355624. The cubic root of 202111981 is about 586.8548340035.

The spelling of 202111981 in words is "two hundred two million, one hundred eleven thousand, nine hundred eighty-one".