71287661 has 4 divisors (see below), whose sum is σ = 71327712. Its totient is φ = 71247612.

The previous prime is 71287651. The next prime is 71287663. The reversal of 71287661 is 16678217.

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 a de Polignac number, because none of the positive numbers 2^k-71287661 is a prime.

It is a super-3 number, since 3×71287661³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71287663) 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, 17225 + ... + 20958.

It is an arithmetic number, because the mean of its divisors is an integer number (17831928).

Almost surely, 2^71287661 is an apocalyptic number.

It is an amenable number.

71287661 is a deficient number, since it is larger than the sum of its proper divisors (40051).

71287661 is a wasteful number, since it uses less digits than its factorization.

71287661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40050.

The product of its digits is 28224, while the sum is 38.

The square root of 71287661 is about 8443.2020584610. The cubic root of 71287661 is about 414.6402475762.

The spelling of 71287661 in words is "seventy-one million, two hundred eighty-seven thousand, six hundred sixty-one".