1816637213 has 4 divisors (see below), whose sum is σ = 1817072220. Its totient is φ = 1816202208.

The previous prime is 1816637209. The next prime is 1816637219. The reversal of 1816637213 is 3127366181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3127366181 = 71 ⋅44047411.

It can be written as a sum of positive squares in 2 ways, for example, as 1718765764 + 97871449 = 41458^2 + 9893^2 .

It is a cyclic number.

It is not a de Polignac number, because 1816637213 - 2² = 1816637209 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 (1816637219) 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, 211178 + ... + 219611.

It is an arithmetic number, because the mean of its divisors is an integer number (454268055).

Almost surely, 2^1816637213 is an apocalyptic number.

It is an amenable number.

1816637213 is a deficient number, since it is larger than the sum of its proper divisors (435007).

1816637213 is an equidigital number, since it uses as much as digits as its factorization.

1816637213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435006.

The product of its digits is 36288, while the sum is 38.

The square root of 1816637213 is about 42622.0273215623. The cubic root of 1816637213 is about 1220.1767219140.

The spelling of 1816637213 in words is "one billion, eight hundred sixteen million, six hundred thirty-seven thousand, two hundred thirteen".