71808661 has 2 divisors, whose sum is σ = 71808662. Its totient is φ = 71808660.

The previous prime is 71808643. The next prime is 71808683. The reversal of 71808661 is 16680817.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39250225 + 32558436 = 6265^2 + 5706^2 .

It is a cyclic number.

It is not a de Polignac number, because 71808661 - 2⁷ = 71808533 is a prime.

It is a super-2 number, since 2×71808661² = 10312967589225842, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 71808661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71808631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35904330 + 35904331.

It is an arithmetic number, because the mean of its divisors is an integer number (35904331).

Almost surely, 2^71808661 is an apocalyptic number.

It is an amenable number.

71808661 is a deficient number, since it is larger than the sum of its proper divisors (1).

71808661 is an equidigital number, since it uses as much as digits as its factorization.

71808661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 71808661 is about 8473.9991149398. Note that the first 3 decimals coincide. The cubic root of 71808661 is about 415.6479180910.

The spelling of 71808661 in words is "seventy-one million, eight hundred eight thousand, six hundred sixty-one".