2172691 has 4 divisors (see below), whose sum is σ = 2198952. Its totient is φ = 2146432.

The previous prime is 2172679. The next prime is 2172701. The reversal of 2172691 is 1962712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2172691 - 2⁵ = 2172659 is a prime.

It is a super-3 number, since 3×2172691³ = 30769125333684406113, which contains 333 as substring.

It is a Duffinian number.

2172691 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2172641) 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, 13006 + ... + 13171.

It is an arithmetic number, because the mean of its divisors is an integer number (549738).

2^2172691 is an apocalyptic number.

2172691 is a deficient number, since it is larger than the sum of its proper divisors (26261).

2172691 is an equidigital number, since it uses as much as digits as its factorization.

2172691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26260.

The product of its digits is 1512, while the sum is 28.

The square root of 2172691 is about 1474.0050881866. The cubic root of 2172691 is about 129.5187532161.

It can be divided in two parts, 21726 and 91, that multiplied together give a triangular number (1977066 = T₁₉₈₈).

The spelling of 2172691 in words is "two million, one hundred seventy-two thousand, six hundred ninety-one".