2136191681 has 4 divisors (see below), whose sum is σ = 2300514132. Its totient is φ = 1971869232.

The previous prime is 2136191671. The next prime is 2136191699. The reversal of 2136191681 is 1861916312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 141229456 + 1994962225 = 11884^2 + 44665^2 .

It is a cyclic number.

It is not a de Polignac number, because 2136191681 - 2¹⁰ = 2136190657 is a prime.

It is a super-2 number, since 2×2136191681² = 9126629795947211522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2136191611) 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, 82161206 + ... + 82161231.

It is an arithmetic number, because the mean of its divisors is an integer number (575128533).

Almost surely, 2^2136191681 is an apocalyptic number.

It is an amenable number.

2136191681 is a deficient number, since it is larger than the sum of its proper divisors (164322451).

2136191681 is a wasteful number, since it uses less digits than its factorization.

2136191681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164322450.

The product of its digits is 15552, while the sum is 38.

The square root of 2136191681 is about 46218.9536986721. The cubic root of 2136191681 is about 1287.8938612900.

The spelling of 2136191681 in words is "two billion, one hundred thirty-six million, one hundred ninety-one thousand, six hundred eighty-one".