1981800499 has 4 divisors (see below), whose sum is σ = 2264914864. Its totient is φ = 1698686136.

The previous prime is 1981800439. The next prime is 1981800511. The reversal of 1981800499 is 9940081891.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1981800499 - 2⁷ = 1981800371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981800419) 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 3 ways as a sum of consecutive naturals, for example, 141557172 + ... + 141557185.

It is an arithmetic number, because the mean of its divisors is an integer number (566228716).

Almost surely, 2^1981800499 is an apocalyptic number.

1981800499 is a deficient number, since it is larger than the sum of its proper divisors (283114365).

1981800499 is an equidigital number, since it uses as much as digits as its factorization.

1981800499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283114364.

The product of its (nonzero) digits is 186624, while the sum is 49.

The square root of 1981800499 is about 44517.4179282671. The cubic root of 1981800499 is about 1256.0877431619.

The spelling of 1981800499 in words is "one billion, nine hundred eighty-one million, eight hundred thousand, four hundred ninety-nine".