78324561221 has 4 divisors (see below), whose sum is σ = 80441441292. Its totient is φ = 76207681152.

The previous prime is 78324561209. The next prime is 78324561253. The reversal of 78324561221 is 12216542387.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 74019364225 + 4305196996 = 272065^2 + 65614^2 .

It is a cyclic number.

It is not a de Polignac number, because 78324561221 - 2³⁰ = 77250819397 is a prime.

It is a super-2 number, since 2×78324561221² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78324564221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1058439980 + ... + 1058440053.

It is an arithmetic number, because the mean of its divisors is an integer number (20110360323).

Almost surely, 2^78324561221 is an apocalyptic number.

It is an amenable number.

78324561221 is a deficient number, since it is larger than the sum of its proper divisors (2116880071).

78324561221 is a wasteful number, since it uses less digits than its factorization.

78324561221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2116880070.

The product of its digits is 161280, while the sum is 41.

The spelling of 78324561221 in words is "seventy-eight billion, three hundred twenty-four million, five hundred sixty-one thousand, two hundred twenty-one".