71780 has 24 divisors (see below), whose sum is σ = 156408. Its totient is φ = 27648.

The previous prime is 71777. The next prime is 71789. The reversal of 71780 is 8717.

It can be written as a sum of positive squares in 4 ways, for example, as 17956 + 53824 = 134^2 + 232^2 .

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (71789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 692 + ... + 788.

It is an arithmetic number, because the mean of its divisors is an integer number (6517).

2⁷¹⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 71780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78204).

71780 is an abundant number, since it is smaller than the sum of its proper divisors (84628).

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

71780 is a wasteful number, since it uses less digits than its factorization.

71780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 23.

The square root of 71780 is about 267.9178978717. The cubic root of 71780 is about 41.5592611530.

It can be divided in two parts, 717 and 80, that added together give a palindrome (797).

The spelling of 71780 in words is "seventy-one thousand, seven hundred eighty".