71809779109 has 4 divisors (see below), whose sum is σ = 73479774016. Its totient is φ = 70139784204.

The previous prime is 71809779089. The next prime is 71809779133. The reversal of 71809779109 is 90197790817.

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.

It is a cyclic number.

It is not a de Polignac number, because 71809779109 - 2¹⁷ = 71809648037 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 (71809779809) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 834997389 + ... + 834997474.

It is an arithmetic number, because the mean of its divisors is an integer number (18369943504).

Almost surely, 2^71809779109 is an apocalyptic number.

It is an amenable number.

71809779109 is a deficient number, since it is larger than the sum of its proper divisors (1669994907).

71809779109 is a wasteful number, since it uses less digits than its factorization.

71809779109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1669994906.

The product of its (nonzero) digits is 2000376, while the sum is 58.

The spelling of 71809779109 in words is "seventy-one billion, eight hundred nine million, seven hundred seventy-nine thousand, one hundred nine".