78211393569 has 27 divisors (see below), whose sum is σ = 114630539673. Its totient is φ = 51386398272.

The previous prime is 78211393523. The next prime is 78211393577. The reversal of 78211393569 is 96539311287.

The square root of 78211393569 is 279663.

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

78211393569 is a `hidden beast` number, since 78 + 2 + 1 + 1 + 3 + 9 + 3 + 569 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 3976941969 + 74234451600 = 63063^2 + 272460^2 .

It is not a de Polignac number, because 78211393569 - 2¹³ = 78211385377 is a prime.

It is a super-2 number, since 2×78211393569² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78211395569) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 61245559 + ... + 61246835.

Almost surely, 2^78211393569 is an apocalyptic number.

78211393569 is the 279663-rd square number.

78211393569 is the 139832-nd centered octagonal number.

It is an amenable number.

78211393569 is a deficient number, since it is larger than the sum of its proper divisors (36419146104).

78211393569 is an frugal number, since it uses more digits than its factorization.

78211393569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2706 (or 1353 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 54.

The spelling of 78211393569 in words is "seventy-eight billion, two hundred eleven million, three hundred ninety-three thousand, five hundred sixty-nine".