990101012219981 has 2 divisors, whose sum is σ = 990101012219982. Its totient is φ = 990101012219980.

The previous prime is 990101012219951. The next prime is 990101012220077. The reversal of 990101012219981 is 189912210101099.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 927176313184900 + 62924699035081 = 30449570^2 + 7932509^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-990101012219981 is a prime.

It is a super-2 number, since 2×990101012219981² (a number of 31 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (990101012219951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495050506109990 + 495050506109991.

It is an arithmetic number, because the mean of its divisors is an integer number (495050506109991).

Almost surely, 2^{990101012219981} is an apocalyptic number.

It is an amenable number.

990101012219981 is a deficient number, since it is larger than the sum of its proper divisors (1).

990101012219981 is an equidigital number, since it uses as much as digits as its factorization.

990101012219981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 53.

The spelling of 990101012219981 in words is "nine hundred ninety trillion, one hundred one billion, twelve million, two hundred nineteen thousand, nine hundred eighty-one".