80661 has 16 divisors (see below), whose sum is σ = 129024. Its totient is φ = 43824.

The previous prime is 80657. The next prime is 80669. The reversal of 80661 is 16608.

It is not a de Polignac number, because 80661 - 2² = 80657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (80669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 400 + ... + 566.

It is an arithmetic number, because the mean of its divisors is an integer number (8064).

2⁸⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

80661 is a deficient number, since it is larger than the sum of its proper divisors (48363).

80661 is a wasteful number, since it uses less digits than its factorization.

80661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 80661 is about 284.0088026805. The cubic root of 80661 is about 43.2070418905.

It can be divided in two parts, 80 and 661, that added together give a triangular number (741 = T₃₈).

The spelling of 80661 in words is "eighty thousand, six hundred sixty-one".