1981800819 has 24 divisors (see below), whose sum is σ = 2990306592. Its totient is φ = 1262384640.

The previous prime is 1981800817. The next prime is 1981800851. The reversal of 1981800819 is 9180081891.

It is not a de Polignac number, because 1981800819 - 2¹ = 1981800817 is a prime.

It is a super-2 number, since 2×1981800819² = 7855068972378141522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1981800817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 206659 + ... + 216035.

It is an arithmetic number, because the mean of its divisors is an integer number (124596108).

Almost surely, 2^1981800819 is an apocalyptic number.

1981800819 is a deficient number, since it is larger than the sum of its proper divisors (1008505773).

1981800819 is a wasteful number, since it uses less digits than its factorization.

1981800819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10427 (or 10424 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 45.

The square root of 1981800819 is about 44517.4215223658. The cubic root of 1981800819 is about 1256.0878107685.

The spelling of 1981800819 in words is "one billion, nine hundred eighty-one million, eight hundred thousand, eight hundred nineteen".