8781661 has 4 divisors (see below), whose sum is σ = 10036192. Its totient is φ = 7527132.

The previous prime is 8781659. The next prime is 8781683. The reversal of 8781661 is 1661878.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1661878 = 2 ⋅830939.

It is a cyclic number.

It is not a de Polignac number, because 8781661 - 2¹ = 8781659 is a prime.

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 8781661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8781601) 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, 627255 + ... + 627268.

It is an arithmetic number, because the mean of its divisors is an integer number (2509048).

Almost surely, 2^8781661 is an apocalyptic number.

It is an amenable number.

8781661 is a deficient number, since it is larger than the sum of its proper divisors (1254531).

8781661 is a wasteful number, since it uses less digits than its factorization.

8781661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1254530.

The product of its digits is 16128, while the sum is 37.

The square root of 8781661 is about 2963.3867449255. The cubic root of 8781661 is about 206.3125067968.

The spelling of 8781661 in words is "eight million, seven hundred eighty-one thousand, six hundred sixty-one".