2138891261 has 8 divisors (see below), whose sum is σ = 2438916984. Its totient is φ = 1858222080.

The previous prime is 2138891243. The next prime is 2138891269. The reversal of 2138891261 is 1621988312.

It can be written as a sum of positive squares in 4 ways, for example, as 762036025 + 1376855236 = 27605^2 + 37106^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2138891261 - 2⁶ = 2138891197 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 (2138891269) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4838900 + ... + 4839341.

It is an arithmetic number, because the mean of its divisors is an integer number (304864623).

Almost surely, 2^2138891261 is an apocalyptic number.

It is an amenable number.

2138891261 is a deficient number, since it is larger than the sum of its proper divisors (300025723).

2138891261 is a wasteful number, since it uses less digits than its factorization.

2138891261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9678271.

The product of its digits is 41472, while the sum is 41.

The square root of 2138891261 is about 46248.1487305168. The cubic root of 2138891261 is about 1288.4361517276.

The spelling of 2138891261 in words is "two billion, one hundred thirty-eight million, eight hundred ninety-one thousand, two hundred sixty-one".