2138681 has 4 divisors (see below), whose sum is σ = 2168052. Its totient is φ = 2109312.

The previous prime is 2138677. The next prime is 2138687. The reversal of 2138681 is 1868312.

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 1357225 + 781456 = 1165^2 + 884^2 .

It is a cyclic number.

It is not a de Polignac number, because 2138681 - 2² = 2138677 is a prime.

It is a super-2 number, since 2×2138681² = 9147912839522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2138687) 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, 14576 + ... + 14721.

It is an arithmetic number, because the mean of its divisors is an integer number (542013).

2^2138681 is an apocalyptic number.

It is an amenable number.

2138681 is a deficient number, since it is larger than the sum of its proper divisors (29371).

2138681 is an equidigital number, since it uses as much as digits as its factorization.

2138681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29370.

The product of its digits is 2304, while the sum is 29.

The square root of 2138681 is about 1462.4229894254. The cubic root of 2138681 is about 128.8393930982.

The spelling of 2138681 in words is "two million, one hundred thirty-eight thousand, six hundred eighty-one".