78126552217 has 6 divisors (see below), whose sum is σ = 90881907738. Its totient is φ = 66965616144.

The previous prime is 78126552199. The next prime is 78126552241. The reversal of 78126552217 is 71225562187.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 63970549776 + 14156002441 = 252924^2 + 118979^2 .

It is a de Polignac number, because none of the positive numbers 2^k-78126552217 is a prime.

It is a super-2 number, since 2×78126552217² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78126552017) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 797209668 + ... + 797209765.

It is an arithmetic number, because the mean of its divisors is an integer number (15146984623).

Almost surely, 2^78126552217 is an apocalyptic number.

It is an amenable number.

78126552217 is a deficient number, since it is larger than the sum of its proper divisors (12755355521).

78126552217 is a wasteful number, since it uses less digits than its factorization.

78126552217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1594419447 (or 1594419440 counting only the distinct ones).

The product of its digits is 470400, while the sum is 46.

The spelling of 78126552217 in words is "seventy-eight billion, one hundred twenty-six million, five hundred fifty-two thousand, two hundred seventeen".