1899999981 has 96 divisors (see below), whose sum is σ = 3249866880. Its totient is φ = 1057536000.

The previous prime is 1899999979. The next prime is 1900000043.

1899999981 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1899999981 - 2¹ = 1899999979 is a prime.

It is a super-2 number, since 2×1899999981² = 7219999855600000722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1899999181) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 13868545 + ... + 13868681.

It is an arithmetic number, because the mean of its divisors is an integer number (33852780).

Almost surely, 2^1899999981 is an apocalyptic number.

1899999981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1899999981 is a deficient number, since it is larger than the sum of its proper divisors (1349866899).

1899999981 is a wasteful number, since it uses less digits than its factorization.

1899999981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347 (or 344 counting only the distinct ones).

The product of its digits is 34012224, while the sum is 72.

The square root of 1899999981 is about 43588.9892174618. The cubic root of 1899999981 is about 1238.5623255016.

It can be divided in two parts, 18 and 99999981, that added together give a palindrome (99999999).

The spelling of 1899999981 in words is "one billion, eight hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-one".