1816815539449 has 3 divisors (see below), whose sum is σ = 1816816887343. Its totient is φ = 1816814191556.

The previous prime is 1816815539447. The next prime is 1816815539459. The reversal of 1816815539449 is 9449355186181.

The square root of 1816815539449 is 1347893.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 1327000322025 + 489815217424 = 1151955^2 + 699868^2 .

It is not a de Polignac number, because 1816815539449 - 2¹ = 1816815539447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1816815539447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 673947 + ... + 2021839.

Almost surely, 2^{1816815539449} is an apocalyptic number.

1816815539449 is the 1347893-rd square number.

1816815539449 is the 673947-th centered octagonal number.

It is an amenable number.

1816815539449 is a deficient number, since it is larger than the sum of its proper divisors (1347894).

1816815539449 is an frugal number, since it uses more digits than its factorization.

1816815539449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2695786 (or 1347893 counting only the distinct ones).

The product of its digits is 37324800, while the sum is 64.

Multiplying 1816815539449 by its sum of digits (64), we get a square (116276194524736 = 10783144²).

The spelling of 1816815539449 in words is "one trillion, eight hundred sixteen billion, eight hundred fifteen million, five hundred thirty-nine thousand, four hundred forty-nine".