78649398025 has 27 divisors (see below), whose sum is σ = 107218206823. Its totient is φ = 57188344400.

The previous prime is 78649397987. The next prime is 78649398029. The reversal of 78649398025 is 52089394687.

The square root of 78649398025 is 280445.

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

It can be written as a sum of positive squares in only one way, i.e., 28313783289 + 50335614736 = 168267^2 + 224356^2 .

It is not a de Polignac number, because 78649398025 - 2²³ = 78641009417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78649398029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 15421926 + ... + 15427024.

Almost surely, 2^78649398025 is an apocalyptic number.

78649398025 is the 280445-th square number.

78649398025 is the 140223-rd centered octagonal number.

It is an amenable number.

78649398025 is a deficient number, since it is larger than the sum of its proper divisors (28568808798).

78649398025 is an frugal number, since it uses more digits than its factorization.

78649398025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10230 (or 5115 counting only the distinct ones).

The product of its (nonzero) digits is 26127360, while the sum is 61.

It can be divided in two parts, 78649 and 398025, that added together give a palindrome (476674).

The spelling of 78649398025 in words is "seventy-eight billion, six hundred forty-nine million, three hundred ninety-eight thousand, twenty-five".