1981899877 has 4 divisors (see below), whose sum is σ = 1982109376. Its totient is φ = 1981690380.

The previous prime is 1981899859. The next prime is 1981899923. The reversal of 1981899877 is 7789981891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7789981891 = 1439 ⋅5413469.

It is a cyclic number.

It is not a de Polignac number, because 1981899877 - 2¹¹ = 1981897829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981899847) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89853 + ... + 109714.

It is an arithmetic number, because the mean of its divisors is an integer number (495527344).

Almost surely, 2^1981899877 is an apocalyptic number.

It is an amenable number.

1981899877 is a deficient number, since it is larger than the sum of its proper divisors (209499).

1981899877 is an equidigital number, since it uses as much as digits as its factorization.

1981899877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209498.

The product of its digits is 18289152, while the sum is 67.

The square root of 1981899877 is about 44518.5340841317. The cubic root of 1981899877 is about 1256.1087384473.

The spelling of 1981899877 in words is "one billion, nine hundred eighty-one million, eight hundred ninety-nine thousand, eight hundred seventy-seven".