18226973721636 has 81 divisors (see below), whose sum is σ = 48165597986961. Its totient is φ = 5811311018304.

The previous prime is 18226973721631. The next prime is 18226973721643. The reversal of 18226973721636 is 63612737962281.

It is a happy number.

The square root of 18226973721636 is 4269306.

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

18226973721636 is a `hidden beast` number, since 1 + 8 + 226 + 9 + 7 + 372 + 1 + 6 + 36 = 666.

It can be written as a sum of positive squares in only one way, i.e., 2113621668900 + 16113352052736 = 1453830^2 + 4014144^2 .

It is not an unprimeable number, because it can be changed into a prime (18226973721631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 589148760 + ... + 589179696.

Almost surely, 2^{18226973721636} is an apocalyptic number.

18226973721636 is the 4269306-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18226973721636

18226973721636 is an abundant number, since it is smaller than the sum of its proper divisors (29938624265325).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18226973721636 is an frugal number, since it uses more digits than its factorization.

18226973721636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61930 (or 30965 counting only the distinct ones).

The product of its digits is 54867456, while the sum is 63.

It can be divided in two parts, 18226973 and 721636, that added together give a square (18948609 = 4353²).

The spelling of 18226973721636 in words is "eighteen trillion, two hundred twenty-six billion, nine hundred seventy-three million, seven hundred twenty-one thousand, six hundred thirty-six".