71720767566 has 144 divisors (see below), whose sum is σ = 192640840704. Its totient is φ = 19183415328.

The previous prime is 71720767523. The next prime is 71720767597. The reversal of 71720767566 is 66576702717.

71720767566 is a `hidden beast` number, since 7 + 1 + 7 + 2 + 0 + 76 + 7 + 566 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 915831 + ... + 991053.

It is an arithmetic number, because the mean of its divisors is an integer number (1337783616).

Almost surely, 2^71720767566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 71720767566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96320420352).

71720767566 is an abundant number, since it is smaller than the sum of its proper divisors (120920073138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

71720767566 is a wasteful number, since it uses less digits than its factorization.

71720767566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75315 (or 75305 counting only the distinct ones).

The product of its (nonzero) digits is 5186160, while the sum is 54.

The spelling of 71720767566 in words is "seventy-one billion, seven hundred twenty million, seven hundred sixty-seven thousand, five hundred sixty-six".