2138648891 has 4 divisors (see below), whose sum is σ = 2138988384. Its totient is φ = 2138309400.

The previous prime is 2138648833. The next prime is 2138648917. The reversal of 2138648891 is 1988468312.

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

It is a cyclic number.

It is not a de Polignac number, because 2138648891 - 2¹⁰ = 2138647867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2138648591) 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, 160115 + ... + 172956.

It is an arithmetic number, because the mean of its divisors is an integer number (534747096).

Almost surely, 2^2138648891 is an apocalyptic number.

2138648891 is a deficient number, since it is larger than the sum of its proper divisors (339493).

2138648891 is an equidigital number, since it uses as much as digits as its factorization.

2138648891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 339492.

The product of its digits is 663552, while the sum is 50.

The square root of 2138648891 is about 46245.5283351807. The cubic root of 2138648891 is about 1288.3874831998.

The spelling of 2138648891 in words is "two billion, one hundred thirty-eight million, six hundred forty-eight thousand, eight hundred ninety-one".