81742661 has 32 divisors (see below), whose sum is σ = 110788608. Its totient is φ = 58242240.

The previous prime is 81742637. The next prime is 81742709. The reversal of 81742661 is 16624718.

It is not a de Polignac number, because 81742661 - 2⁶ = 81742597 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81744661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 126806 + ... + 127448.

It is an arithmetic number, because the mean of its divisors is an integer number (3462144).

Almost surely, 2^81742661 is an apocalyptic number.

It is an amenable number.

81742661 is a deficient number, since it is larger than the sum of its proper divisors (29045947).

81742661 is a wasteful number, since it uses less digits than its factorization.

81742661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801.

The product of its digits is 16128, while the sum is 35.

The square root of 81742661 is about 9041.1648032762. The cubic root of 81742661 is about 433.9931989420.

The spelling of 81742661 in words is "eighty-one million, seven hundred forty-two thousand, six hundred sixty-one".