81766157 has 4 divisors (see below), whose sum is σ = 89199456. Its totient is φ = 74332860.

The previous prime is 81766151. The next prime is 81766159. The reversal of 81766157 is 75166718.

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 81766157 - 2¹⁰ = 81765133 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 (81766151) 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, 3716633 + ... + 3716654.

It is an arithmetic number, because the mean of its divisors is an integer number (22299864).

Almost surely, 2^81766157 is an apocalyptic number.

It is an amenable number.

81766157 is a deficient number, since it is larger than the sum of its proper divisors (7433299).

81766157 is a wasteful number, since it uses less digits than its factorization.

81766157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7433298.

The product of its digits is 70560, while the sum is 41.

The square root of 81766157 is about 9042.4641000117. The cubic root of 81766157 is about 434.0347770981.

It can be divided in two parts, 817661 and 57, that added together give a palindrome (817718).

The spelling of 81766157 in words is "eighty-one million, seven hundred sixty-six thousand, one hundred fifty-seven".