81717505586 has 4 divisors (see below), whose sum is σ = 122576258382. Its totient is φ = 40858752792.

The previous prime is 81717505559. The next prime is 81717505589. The reversal of 81717505586 is 68550571718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 66669822025 + 15047683561 = 258205^2 + 122669^2 .

It is not an unprimeable number, because it can be changed into a prime (81717505589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20429376395 + ... + 20429376398.

Almost surely, 2^81717505586 is an apocalyptic number.

81717505586 is a deficient number, since it is larger than the sum of its proper divisors (40858752796).

81717505586 is a wasteful number, since it uses less digits than its factorization.

81717505586 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40858752795.

The product of its (nonzero) digits is 2352000, while the sum is 53.

The spelling of 81717505586 in words is "eighty-one billion, seven hundred seventeen million, five hundred five thousand, five hundred eighty-six".