101021111981 has 2 divisors, whose sum is σ = 101021111982. Its totient is φ = 101021111980.

The previous prime is 101021111953. The next prime is 101021112013. The reversal of 101021111981 is 189111120101.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52319242756 + 48701869225 = 228734^2 + 220685^2 .

It is an emirp because it is prime and its reverse (189111120101) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-101021111981 is a prime.

It is a super-2 number, since 2×101021111981² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 101021111981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (101021111281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50510555990 + 50510555991.

It is an arithmetic number, because the mean of its divisors is an integer number (50510555991).

Almost surely, 2^101021111981 is an apocalyptic number.

It is an amenable number.

101021111981 is a deficient number, since it is larger than the sum of its proper divisors (1).

101021111981 is an equidigital number, since it uses as much as digits as its factorization.

101021111981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 26.

The spelling of 101021111981 in words is "one hundred one billion, twenty-one million, one hundred eleven thousand, nine hundred eighty-one".