2179809 has 6 divisors (see below), whose sum is σ = 3148626. Its totient is φ = 1453200.

The previous prime is 2179787. The next prime is 2179811. The reversal of 2179809 is 9089712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 2039184 + 140625 = 1428^2 + 375^2 .

It is not a de Polignac number, because 2179809 - 2⁵ = 2179777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2179819) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 121092 + ... + 121109.

It is an arithmetic number, because the mean of its divisors is an integer number (524771).

2^2179809 is an apocalyptic number.

It is an amenable number.

2179809 is a deficient number, since it is larger than the sum of its proper divisors (968817).

2179809 is a wasteful number, since it uses less digits than its factorization.

2179809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242207 (or 242204 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 2179809 is about 1476.4176238450. The cubic root of 2179809 is about 129.6600387687.

Subtracting 2179809 from its reverse (9089712), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2179809 in words is "two million, one hundred seventy-nine thousand, eight hundred nine".