71578186681 has 3 divisors (see below), whose sum is σ = 71578454223. Its totient is φ = 71577919140.

The previous prime is 71578186661. The next prime is 71578186697. The reversal of 71578186681 is 18668187517.

The square root of 71578186681 is 267541.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 21464887081 + 50113299600 = 146509^2 + 223860^2 .

It is not a de Polignac number, because 71578186681 - 2²⁹ = 71041315769 is a prime.

It is a super-2 number, since 2×71578186681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71578186661) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 133771 + ... + 401311.

It is an arithmetic number, because the mean of its divisors is an integer number (23859484741).

Almost surely, 2^71578186681 is an apocalyptic number.

71578186681 is the 267541-st square number.

71578186681 is the 133771-st centered octagonal number.

It is an amenable number.

71578186681 is a deficient number, since it is larger than the sum of its proper divisors (267542).

71578186681 is an frugal number, since it uses more digits than its factorization.

71578186681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 535082 (or 267541 counting only the distinct ones).

The product of its digits is 4515840, while the sum is 58.

The spelling of 71578186681 in words is "seventy-one billion, five hundred seventy-eight million, one hundred eighty-six thousand, six hundred eighty-one".