181660861 has 16 divisors (see below), whose sum is σ = 198362736. Its totient is φ = 165666816.

The previous prime is 181660859. The next prime is 181660889. The reversal of 181660861 is 168066181.

181660861 = 9530² + 9531².

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 43480836 + 138180025 = 6594^2 + 11755^2 .

It is a cyclic number.

It is not a de Polignac number, because 181660861 - 2¹ = 181660859 is a prime.

It is a super-2 number, since 2×181660861² = 66001336838522642, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 181660861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181660841) 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, 211545 + ... + 212401.

It is an arithmetic number, because the mean of its divisors is an integer number (12397671).

Almost surely, 2^181660861 is an apocalyptic number.

181660861 is the 9531-st centered square number.

It is an amenable number.

181660861 is a deficient number, since it is larger than the sum of its proper divisors (16701875).

181660861 is a wasteful number, since it uses less digits than its factorization.

181660861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1248.

The product of its (nonzero) digits is 13824, while the sum is 37.

The square root of 181660861 is about 13478.1623747453. The cubic root of 181660861 is about 566.3528923022.

The spelling of 181660861 in words is "one hundred eighty-one million, six hundred sixty thousand, eight hundred sixty-one".