81766572 has 12 divisors (see below), whose sum is σ = 190788696. Its totient is φ = 27255520.

The previous prime is 81766571. The next prime is 81766577. The reversal of 81766572 is 27566718.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

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 3 ways as a sum of consecutive naturals, for example, 3406929 + ... + 3406952.

It is an arithmetic number, because the mean of its divisors is an integer number (15899058).

Almost surely, 2^81766572 is an apocalyptic number.

It is an amenable number.

81766572 is an abundant number, since it is smaller than the sum of its proper divisors (109022124).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81766572 is a wasteful number, since it uses less digits than its factorization.

81766572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6813888 (or 6813886 counting only the distinct ones).

The product of its digits is 141120, while the sum is 42.

The square root of 81766572 is about 9042.4870472675. The cubic root of 81766572 is about 434.0355114040.

The spelling of 81766572 in words is "eighty-one million, seven hundred sixty-six thousand, five hundred seventy-two".