78781823761 has 3 divisors (see below), whose sum is σ = 78782104443. Its totient is φ = 78781543080.

The previous prime is 78781823737. The next prime is 78781823773. The reversal of 78781823761 is 16732818787.

The square root of 78781823761 is 280681.

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., 202521361 + 78579302400 = 14231^2 + 280320^2 .

It is not a de Polignac number, because 78781823761 - 2⁷ = 78781823633 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78781823696 and 78781823705.

It is not an unprimeable number, because it can be changed into a prime (78781823711) 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, 140341 + ... + 421021.

It is an arithmetic number, because the mean of its divisors is an integer number (26260701481).

Almost surely, 2^78781823761 is an apocalyptic number.

78781823761 is the 280681-st square number.

78781823761 is the 140341-st centered octagonal number.

It is an amenable number.

78781823761 is a deficient number, since it is larger than the sum of its proper divisors (280682).

78781823761 is an frugal number, since it uses more digits than its factorization.

78781823761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561362 (or 280681 counting only the distinct ones).

The product of its digits is 6322176, while the sum is 58.

The spelling of 78781823761 in words is "seventy-eight billion, seven hundred eighty-one million, eight hundred twenty-three thousand, seven hundred sixty-one".