2157609 has 4 divisors (see below), whose sum is σ = 2876816. Its totient is φ = 1438404.

The previous prime is 2157587. The next prime is 2157641. The reversal of 2157609 is 9067512.

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.

It is not a de Polignac number, because 2157609 - 2⁷ = 2157481 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2157679) 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, 359599 + ... + 359604.

It is an arithmetic number, because the mean of its divisors is an integer number (719204).

2^2157609 is an apocalyptic number.

It is an amenable number.

2157609 is a deficient number, since it is larger than the sum of its proper divisors (719207).

2157609 is an equidigital number, since it uses as much as digits as its factorization.

2157609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 719206.

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 2157609 is about 1468.8801857197. The cubic root of 2157609 is about 129.2183670016.

Subtracting 2157609 from its reverse (9067512), we obtain a triangular number (6909903 = T₃₇₁₇).

It can be divided in two parts, 21 and 57609, that added together give a triangular number (57630 = T₃₃₉).

The spelling of 2157609 in words is "two million, one hundred fifty-seven thousand, six hundred nine".