7842738639121 has 3 divisors (see below), whose sum is σ = 7842741439611. Its totient is φ = 7842735838632.

The previous prime is 7842738639089. The next prime is 7842738639133. The reversal of 7842738639121 is 1219368372487.

The square root of 7842738639121 is 2800489.

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., 6649750421521 + 1192988217600 = 2578711^2 + 1092240^2 .

It is not a de Polignac number, because 7842738639121 - 2⁵ = 7842738639089 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 7842738639121.

It is not an unprimeable number, because it can be changed into a prime (7842738639161) 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 2 ways as a sum of consecutive naturals, for example, 1400245 + ... + 4200733.

It is an arithmetic number, because the mean of its divisors is an integer number (2614247146537).

Almost surely, 2^{7842738639121} is an apocalyptic number.

7842738639121 is the 2800489-th square number.

7842738639121 is the 1400245-th centered octagonal number.

It is an amenable number.

7842738639121 is a deficient number, since it is larger than the sum of its proper divisors (2800490).

7842738639121 is an frugal number, since it uses more digits than its factorization.

7842738639121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5600978 (or 2800489 counting only the distinct ones).

The product of its digits is 24385536, while the sum is 61.

The spelling of 7842738639121 in words is "seven trillion, eight hundred forty-two billion, seven hundred thirty-eight million, six hundred thirty-nine thousand, one hundred twenty-one".