1985885891 has 4 divisors (see below), whose sum is σ = 2166420984. Its totient is φ = 1805350800.

The previous prime is 1985885827. The next prime is 1985885893.

1985885891 is nontrivially palindromic in base 10.

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

It is not a de Polignac number, because 1985885891 - 2⁶ = 1985885827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1985885893) 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, 90267530 + ... + 90267551.

It is an arithmetic number, because the mean of its divisors is an integer number (541605246).

Almost surely, 2^1985885891 is an apocalyptic number.

1985885891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1985885891 is a deficient number, since it is larger than the sum of its proper divisors (180535093).

1985885891 is a wasteful number, since it uses less digits than its factorization.

1985885891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180535092.

The product of its digits is 8294400, while the sum is 62.

The square root of 1985885891 is about 44563.2796257188. The cubic root of 1985885891 is about 1256.9502734146.

The spelling of 1985885891 in words is "one billion, nine hundred eighty-five million, eight hundred eighty-five thousand, eight hundred ninety-one".