2109645 has 20 divisors (see below), whose sum is σ = 3782460. Its totient is φ = 1124928.

The previous prime is 2109641. The next prime is 2109647. The reversal of 2109645 is 5469012.

2109645 is a `hidden beast` number, since 2 + 10 + 9 + 645 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1565001 + 544644 = 1251^2 + 738^2 .

It is not a de Polignac number, because 2109645 - 2² = 2109641 is a prime.

It is a super-3 number, since 3×2109645³ = 28167570933580533375, which contains 333 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2109641) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2200 + ... + 3009.

It is an arithmetic number, because the mean of its divisors is an integer number (189123).

2^2109645 is an apocalyptic number.

It is an amenable number.

2109645 is a deficient number, since it is larger than the sum of its proper divisors (1672815).

2109645 is an equidigital number, since it uses as much as digits as its factorization.

2109645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5226 (or 5217 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 2109645 is about 1452.4617034538. The cubic root of 2109645 is about 128.2536676903.

The spelling of 2109645 in words is "two million, one hundred nine thousand, six hundred forty-five".