8640661 has 8 divisors (see below), whose sum is σ = 8968448. Its totient is φ = 8316000.

The previous prime is 8640601. The next prime is 8640679. The reversal of 8640661 is 1660468.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 8640661 - 2¹⁹ = 8116373 is a prime.

It is a super-2 number, since 2×8640661² = 149322045033842, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is the 2940-th Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8640601) by changing a digit.

It is a nontrivial repunit in base 2939.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5881 + ... + 7201.

It is an arithmetic number, because the mean of its divisors is an integer number (1121056).

It is a Poulet number, since it divides 2^8640660-1.

Almost surely, 2^8640661 is an apocalyptic number.

It is an amenable number.

8640661 is a deficient number, since it is larger than the sum of its proper divisors (327787).

8640661 is a wasteful number, since it uses less digits than its factorization.

8640661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1563.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 8640661 is about 2939.5001275727. The cubic root of 8640661 is about 205.2023463108.

The spelling of 8640661 in words is "eight million, six hundred forty thousand, six hundred sixty-one".