2121865 has 8 divisors (see below), whose sum is σ = 2657088. Its totient is φ = 1623600.

The previous prime is 2121853. The next prime is 2121869. The reversal of 2121865 is 5681212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2121865 - 2⁷ = 2121737 is a prime.

It is a super-2 number, since 2×2121865² = 9004622156450, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2121869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9111 + ... + 9340.

It is an arithmetic number, because the mean of its divisors is an integer number (332136).

2^2121865 is an apocalyptic number.

It is an amenable number.

2121865 is a deficient number, since it is larger than the sum of its proper divisors (535223).

2121865 is a wasteful number, since it uses less digits than its factorization.

2121865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18479.

The product of its digits is 960, while the sum is 25.

The square root of 2121865 is about 1456.6622806952. The cubic root of 2121865 is about 128.5008251397.

The spelling of 2121865 in words is "two million, one hundred twenty-one thousand, eight hundred sixty-five".