78619928221 has 4 divisors (see below), whose sum is σ = 82757819200. Its totient is φ = 74482037244.

The previous prime is 78619928173. The next prime is 78619928291. The reversal of 78619928221 is 12282991687.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12282991687 = 191 ⋅64308857.

It is a cyclic number.

It is not a de Polignac number, because 78619928221 - 2¹⁷ = 78619797149 is a prime.

It is a super-2 number, since 2×78619928221² (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 (78619928291) 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 3 ways as a sum of consecutive naturals, for example, 2068945461 + ... + 2068945498.

It is an arithmetic number, because the mean of its divisors is an integer number (20689454800).

Almost surely, 2^78619928221 is an apocalyptic number.

It is an amenable number.

78619928221 is a deficient number, since it is larger than the sum of its proper divisors (4137890979).

78619928221 is a wasteful number, since it uses less digits than its factorization.

78619928221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4137890978.

The product of its digits is 1741824, while the sum is 55.

The spelling of 78619928221 in words is "seventy-eight billion, six hundred nineteen million, nine hundred twenty-eight thousand, two hundred twenty-one".