1940138209 has 9 divisors (see below), whose sum is σ = 2061773011. Its totient is φ = 1825307680.

The previous prime is 1940138191. The next prime is 1940138237. The reversal of 1940138209 is 9028310491.

The square root of 1940138209 is 44047.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1510488225 + 429649984 = 38865^2 + 20728^2 .

It is not a de Polignac number, because 1940138209 - 2¹⁵ = 1940105441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1940138909) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 747504 + ... + 750094.

Almost surely, 2^1940138209 is an apocalyptic number.

1940138209 is the 44047-th square number.

1940138209 is the 22024-th centered octagonal number.

It is an amenable number.

1940138209 is a deficient number, since it is larger than the sum of its proper divisors (121634802).

1940138209 is an frugal number, since it uses more digits than its factorization.

With its predecessor (1940138208) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (5216).

1940138209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5216 (or 2608 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The cubic root of 1940138209 is about 1247.2233211976.

The spelling of 1940138209 in words is "one billion, nine hundred forty million, one hundred thirty-eight thousand, two hundred nine".