78686421121 has 27 divisors (see below), whose sum is σ = 100638480033. Its totient is φ = 61297263720.

The previous prime is 78686421103. The next prime is 78686421127. The reversal of 78686421121 is 12112468687.

The square root of 78686421121 is 280511.

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

It is not a de Polignac number, because 78686421121 - 2³⁵ = 44326682753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78686421127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 21597526 + ... + 21601168.

Almost surely, 2^78686421121 is an apocalyptic number.

78686421121 is the 280511-st square number.

78686421121 is the 140256-th centered octagonal number.

It is an amenable number.

78686421121 is a deficient number, since it is larger than the sum of its proper divisors (21952058912).

78686421121 is an frugal number, since it uses more digits than its factorization.

78686421121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7322 (or 3661 counting only the distinct ones).

The product of its digits is 258048, while the sum is 46.

The spelling of 78686421121 in words is "seventy-eight billion, six hundred eighty-six million, four hundred twenty-one thousand, one hundred twenty-one".