79689787421 has 4 divisors (see below), whose sum is σ = 79718363100. Its totient is φ = 79661211744.

The previous prime is 79689787361. The next prime is 79689787423. The reversal of 79689787421 is 12478798697.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12478798697 = 21737 ⋅574081.

It can be written as a sum of positive squares in 2 ways, for example, as 18254712100 + 61435075321 = 135110^2 + 247861^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-79689787421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79689787423) 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, 14283656 + ... + 14289233.

It is an arithmetic number, because the mean of its divisors is an integer number (19929590775).

Almost surely, 2^79689787421 is an apocalyptic number.

It is an amenable number.

79689787421 is a deficient number, since it is larger than the sum of its proper divisors (28575679).

79689787421 is a wasteful number, since it uses less digits than its factorization.

79689787421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28575678.

The product of its digits is 85349376, while the sum is 68.

The spelling of 79689787421 in words is "seventy-nine billion, six hundred eighty-nine million, seven hundred eighty-seven thousand, four hundred twenty-one".