81766531 has 8 divisors (see below), whose sum is σ = 101942784. Its totient is φ = 63714120.

The previous prime is 81766523. The next prime is 81766543. The reversal of 81766531 is 13566718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81766531 - 2³ = 81766523 is a prime.

It is a super-2 number, since 2×81766531² = 13371531183547922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81766571) 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, 530875 + ... + 531028.

It is an arithmetic number, because the mean of its divisors is an integer number (12742848).

Almost surely, 2^81766531 is an apocalyptic number.

81766531 is a deficient number, since it is larger than the sum of its proper divisors (20176253).

81766531 is a wasteful number, since it uses less digits than its factorization.

81766531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061921.

The product of its digits is 30240, while the sum is 37.

The square root of 81766531 is about 9042.4847801918. The cubic root of 81766531 is about 434.0354388583.

The spelling of 81766531 in words is "eighty-one million, seven hundred sixty-six thousand, five hundred thirty-one".