1999901081 has 2 divisors, whose sum is σ = 1999901082. Its totient is φ = 1999901080.

The previous prime is 1999901053. The next prime is 1999901087. The reversal of 1999901081 is 1801099991.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1890510400 + 109390681 = 43480^2 + 10459^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999901081 - 2¹⁰ = 1999900057 is a prime.

It is a super-2 number, since 2×1999901081² = 7999208667569937122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1999901087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999950540 + 999950541.

It is an arithmetic number, because the mean of its divisors is an integer number (999950541).

Almost surely, 2^1999901081 is an apocalyptic number.

It is an amenable number.

1999901081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999901081 is an equidigital number, since it uses as much as digits as its factorization.

1999901081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 52488, while the sum is 47.

The square root of 1999901081 is about 44720.2535882792. The cubic root of 1999901081 is about 1259.9002778640.

The spelling of 1999901081 in words is "one billion, nine hundred ninety-nine million, nine hundred one thousand, eighty-one".