1899779981 has 6 divisors (see below), whose sum is σ = 2088188046. Its totient is φ = 1727072600.

The previous prime is 1899779957. The next prime is 1899779993.

1899779981 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 1234397956 + 665382025 = 35134^2 + 25795^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1899779981 is a prime.

It is a super-2 number, since 2×1899779981² = 7218327952416720722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1899779081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7850210 + ... + 7850451.

It is an arithmetic number, because the mean of its divisors is an integer number (348031341).

Almost surely, 2^1899779981 is an apocalyptic number.

1899779981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1899779981 is a deficient number, since it is larger than the sum of its proper divisors (188408065).

1899779981 is a wasteful number, since it uses less digits than its factorization.

1899779981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15700683 (or 15700672 counting only the distinct ones).

The product of its digits is 20575296, while the sum is 68.

The square root of 1899779981 is about 43586.4655713216. The cubic root of 1899779981 is about 1238.5145194960.

The spelling of 1899779981 in words is "one billion, eight hundred ninety-nine million, seven hundred seventy-nine thousand, nine hundred eighty-one".