2121405 has 64 divisors (see below), whose sum is σ = 4257792. Its totient is φ = 887040.

The previous prime is 2121403. The next prime is 2121433. The reversal of 2121405 is 5041212.

It is not a de Polignac number, because 2121405 - 2¹ = 2121403 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

2121405 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121403) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 49314 + ... + 49356.

It is an arithmetic number, because the mean of its divisors is an integer number (66528).

2^2121405 is an apocalyptic number.

It is an amenable number.

2121405 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

2121405 is a wasteful number, since it uses less digits than its factorization.

2121405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 2121405 is about 1456.5043769244. The cubic root of 2121405 is about 128.4915385527.

Adding to 2121405 its reverse (5041212), we get a palindrome (7162617).

The spelling of 2121405 in words is "two million, one hundred twenty-one thousand, four hundred five".