101021981 has 2 divisors, whose sum is σ = 101021982. Its totient is φ = 101021980.

The previous prime is 101021969. The next prime is 101022059. The reversal of 101021981 is 189120101.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 93508900 + 7513081 = 9670^2 + 2741^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-101021981 is a prime.

It is a super-2 number, since 2×101021981² = 20410881290328722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (101020981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50510990 + 50510991.

It is an arithmetic number, because the mean of its divisors is an integer number (50510991).

Almost surely, 2^101021981 is an apocalyptic number.

It is an amenable number.

101021981 is a deficient number, since it is larger than the sum of its proper divisors (1).

101021981 is an equidigital number, since it uses as much as digits as its factorization.

101021981 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 23.

The square root of 101021981 is about 10050.9691572505. The cubic root of 101021981 is about 465.7347323978.

The spelling of 101021981 in words is "one hundred one million, twenty-one thousand, nine hundred eighty-one".