81170661 has 32 divisors (see below), whose sum is σ = 127733760. Its totient is φ = 45201600.

The previous prime is 81170659. The next prime is 81170723. The reversal of 81170661 is 16607118.

It is a happy number.

It is not a de Polignac number, because 81170661 - 2¹ = 81170659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81170161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 184680 + ... + 185118.

It is an arithmetic number, because the mean of its divisors is an integer number (3991680).

Almost surely, 2^81170661 is an apocalyptic number.

It is an amenable number.

81170661 is a deficient number, since it is larger than the sum of its proper divisors (46563099).

81170661 is a wasteful number, since it uses less digits than its factorization.

81170661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 81170661 is about 9009.4761778918. The cubic root of 81170661 is about 432.9785292314.

Adding to 81170661 its reverse (16607118), we get a palindrome (97777779).

The spelling of 81170661 in words is "eighty-one million, one hundred seventy thousand, six hundred sixty-one".