988778891 has 4 divisors (see below), whose sum is σ = 988859232. Its totient is φ = 988698552.

The previous prime is 988778881. The next prime is 988778933. The reversal of 988778891 is 198877889.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 988778891 - 2⁶ = 988778827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (988778801) 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, 17411 + ... + 47756.

It is an arithmetic number, because the mean of its divisors is an integer number (247214808).

Almost surely, 2^988778891 is an apocalyptic number.

988778891 is a deficient number, since it is larger than the sum of its proper divisors (80341).

988778891 is a wasteful number, since it uses less digits than its factorization.

988778891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80340.

The product of its digits is 16257024, while the sum is 65.

The square root of 988778891 is about 31444.8547619479. The cubic root of 988778891 is about 996.2455520950.

The spelling of 988778891 in words is "nine hundred eighty-eight million, seven hundred seventy-eight thousand, eight hundred ninety-one".