181615749121 has 4 divisors (see below), whose sum is σ = 181633810644. Its totient is φ = 181597687600.

The previous prime is 181615749101. The next prime is 181615749181. The reversal of 181615749121 is 121947516181.

It is a happy number.

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 39535754896 + 142079994225 = 198836^2 + 376935^2 .

It is a cyclic number.

It is not a de Polignac number, because 181615749121 - 2¹⁵ = 181615716353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181615749101) 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, 9015670 + ... + 9035791.

It is an arithmetic number, because the mean of its divisors is an integer number (45408452661).

Almost surely, 2^181615749121 is an apocalyptic number.

It is an amenable number.

181615749121 is a deficient number, since it is larger than the sum of its proper divisors (18061523).

181615749121 is a wasteful number, since it uses less digits than its factorization.

181615749121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18061522.

The product of its digits is 120960, while the sum is 46.

The spelling of 181615749121 in words is "one hundred eighty-one billion, six hundred fifteen million, seven hundred forty-nine thousand, one hundred twenty-one".