8640405 has 32 divisors (see below), whose sum is σ = 15897600. Its totient is φ = 4447296.

The previous prime is 8640391. The next prime is 8640407. The reversal of 8640405 is 5040468.

It is not a de Polignac number, because 8640405 - 2¹⁰ = 8639381 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8640407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2812 + ... + 5018.

It is an arithmetic number, because the mean of its divisors is an integer number (496800).

Almost surely, 2^8640405 is an apocalyptic number.

It is an amenable number.

8640405 is a deficient number, since it is larger than the sum of its proper divisors (7257195).

8640405 is a wasteful number, since it uses less digits than its factorization.

8640405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2250 (or 2244 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 8640405 is about 2939.4565824315. The cubic root of 8640405 is about 205.2003197560.

It can be divided in two parts, 8640 and 405, that added together give a triangular number (9045 = T₁₃₄).

The spelling of 8640405 in words is "eight million, six hundred forty thousand, four hundred five".