78820001001 has 81 divisors (see below), whose sum is σ = 137461571013. Its totient is φ = 43392565440.

The previous prime is 78820000991. The next prime is 78820001017. The reversal of 78820001001 is 10010002887.

The square root of 78820001001 is 280749.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1980161001 + 76839840000 = 44499^2 + 277200^2 .

It is not a de Polignac number, because 78820001001 - 2⁷ = 78820000873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78820001081) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 170975911 + ... + 170976371.

Almost surely, 2^78820001001 is an apocalyptic number.

78820001001 is the 280749-th square number.

78820001001 is the 140375-th centered octagonal number.

It is an amenable number.

78820001001 is a deficient number, since it is larger than the sum of its proper divisors (58641570012).

78820001001 is an equidigital number, since it uses as much as digits as its factorization.

78820001001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000 (or 500 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

Adding to 78820001001 its reverse (10010002887), we get a palindrome (88830003888).

The spelling of 78820001001 in words is "seventy-eight billion, eight hundred twenty million, one thousand, one".