78511217009 has 4 divisors (see below), whose sum is σ = 78520358004. Its totient is φ = 78502076016.

The previous prime is 78511216957. The next prime is 78511217041. The reversal of 78511217009 is 90071211587.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90071211587 = 7 ⋅12867315941.

It can be written as a sum of positive squares in 2 ways, for example, as 61961166400 + 16550050609 = 248920^2 + 128647^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78511217009 is a prime.

It is a super-2 number, since 2×78511217009² (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 (78511217089) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4557602 + ... + 4574795.

It is an arithmetic number, because the mean of its divisors is an integer number (19630089501).

Almost surely, 2^78511217009 is an apocalyptic number.

It is an amenable number.

78511217009 is a deficient number, since it is larger than the sum of its proper divisors (9140995).

78511217009 is an equidigital number, since it uses as much as digits as its factorization.

78511217009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9140994.

The product of its (nonzero) digits is 35280, while the sum is 41.

The spelling of 78511217009 in words is "seventy-eight billion, five hundred eleven million, two hundred seventeen thousand, nine".