81566701 has 4 divisors (see below), whose sum is σ = 81585504. Its totient is φ = 81547900.

The previous prime is 81566659. The next prime is 81566711. The reversal of 81566701 is 10766518.

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 not a de Polignac number, because 81566701 - 2¹¹ = 81564653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81566711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 786 + ... + 12796.

It is an arithmetic number, because the mean of its divisors is an integer number (20396376).

Almost surely, 2^81566701 is an apocalyptic number.

It is an amenable number.

81566701 is a deficient number, since it is larger than the sum of its proper divisors (18803).

81566701 is a wasteful number, since it uses less digits than its factorization.

81566701 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18802.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 81566701 is about 9031.4285138067. The cubic root of 81566701 is about 433.6815693190.

The spelling of 81566701 in words is "eighty-one million, five hundred sixty-six thousand, seven hundred one".