3865644 has 72 divisors (see below), whose sum is σ = 10487568. Its totient is φ = 1244160.

The previous prime is 3865637. The next prime is 3865663. The reversal of 3865644 is 4465683.

3865644 is a `hidden beast` number, since 3 + 8 + 6 + 5 + 644 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 3865599 and 3865608.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 39804 + ... + 39900.

Almost surely, 2^3865644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 3865644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5243784).

3865644 is an abundant number, since it is smaller than the sum of its proper divisors (6621924).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

3865644 is a wasteful number, since it uses less digits than its factorization.

3865644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157 (or 143 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 3865644 is about 1966.1241059506. The cubic root of 3865644 is about 156.9425188847.

The spelling of 3865644 in words is "three million, eight hundred sixty-five thousand, six hundred forty-four".