1988668891 has 32 divisors (see below), whose sum is σ = 2354075136. Its totient is φ = 1659840000.

The previous prime is 1988668837. The next prime is 1988668909.

1988668891 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 1988668891 - 2¹³ = 1988660699 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1988668391) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1340236 + ... + 1341718.

It is an arithmetic number, because the mean of its divisors is an integer number (73564848).

Almost surely, 2^1988668891 is an apocalyptic number.

1988668891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1988668891 is a deficient number, since it is larger than the sum of its proper divisors (365406245).

1988668891 is a wasteful number, since it uses less digits than its factorization.

1988668891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1683.

The product of its digits is 11943936, while the sum is 64.

The square root of 1988668891 is about 44594.4939538504. The cubic root of 1988668891 is about 1257.5371583970.

The spelling of 1988668891 in words is "one billion, nine hundred eighty-eight million, six hundred sixty-eight thousand, eight hundred ninety-one".