78297178121 has 2 divisors, whose sum is σ = 78297178122. Its totient is φ = 78297178120.

The previous prime is 78297178093. The next prime is 78297178163. The reversal of 78297178121 is 12187179287.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 40248384400 + 38048793721 = 200620^2 + 195061^2 .

It is a cyclic number.

It is not a de Polignac number, because 78297178121 - 2¹⁰ = 78297177097 is a prime.

It is a super-2 number, since 2×78297178121² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78297138121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39148589060 + 39148589061.

It is an arithmetic number, because the mean of its divisors is an integer number (39148589061).

Almost surely, 2^78297178121 is an apocalyptic number.

It is an amenable number.

78297178121 is a deficient number, since it is larger than the sum of its proper divisors (1).

78297178121 is an equidigital number, since it uses as much as digits as its factorization.

78297178121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 790272, while the sum is 53.

The spelling of 78297178121 in words is "seventy-eight billion, two hundred ninety-seven million, one hundred seventy-eight thousand, one hundred twenty-one".