78172817389 has 2 divisors, whose sum is σ = 78172817390. Its totient is φ = 78172817388.

The previous prime is 78172817353. The next prime is 78172817461. The reversal of 78172817389 is 98371827187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 60412724100 + 17760093289 = 245790^2 + 133267^2 .

It is a cyclic number.

It is not a de Polignac number, because 78172817389 - 2²³ = 78164428781 is a prime.

It is a super-2 number, since 2×78172817389² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78172887389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39086408694 + 39086408695.

It is an arithmetic number, because the mean of its divisors is an integer number (39086408695).

Almost surely, 2^78172817389 is an apocalyptic number.

It is an amenable number.

78172817389 is a deficient number, since it is larger than the sum of its proper divisors (1).

78172817389 is an equidigital number, since it uses as much as digits as its factorization.

78172817389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9483264, while the sum is 61.

The spelling of 78172817389 in words is "seventy-eight billion, one hundred seventy-two million, eight hundred seventeen thousand, three hundred eighty-nine".