12018778509721 has 3 divisors (see below), whose sum is σ = 12018781976533. Its totient is φ = 12018775042910.

The previous prime is 12018778509653. The next prime is 12018778509739. The reversal of 12018778509721 is 12790587781021.

It is a happy number.

The square root of 12018778509721 is 3466811.

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 is not a de Polignac number, because 12018778509721 - 2²¹ = 12018776412569 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12018778509821) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1733406 + ... + 5200216.

Almost surely, 2^{12018778509721} is an apocalyptic number.

12018778509721 is the 3466811-st square number.

12018778509721 is the 1733406-th centered octagonal number.

It is an amenable number.

12018778509721 is a deficient number, since it is larger than the sum of its proper divisors (3466812).

12018778509721 is an frugal number, since it uses more digits than its factorization.

12018778509721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6933622 (or 3466811 counting only the distinct ones).

The product of its (nonzero) digits is 3951360, while the sum is 58.

The spelling of 12018778509721 in words is "twelve trillion, eighteen billion, seven hundred seventy-eight million, five hundred nine thousand, seven hundred twenty-one".