2121391 has 4 divisors (see below), whose sum is σ = 2124400. Its totient is φ = 2118384.

The previous prime is 2121389. The next prime is 2121403. The reversal of 2121391 is 1931212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 2121391 - 2¹ = 2121389 is a prime.

It is a d-powerful number, because it can be written as 2¹¹ + 1 + 2¹⁹ + 1 + 3¹³ + 9³ + 1 .

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121341) 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, 190 + ... + 2068.

It is an arithmetic number, because the mean of its divisors is an integer number (531100).

2^2121391 is an apocalyptic number.

2121391 is a deficient number, since it is larger than the sum of its proper divisors (3009).

2121391 is a wasteful number, since it uses less digits than its factorization.

2121391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3008.

The product of its digits is 108, while the sum is 19.

The square root of 2121391 is about 1456.4995708891. The cubic root of 2121391 is about 128.4912558964.

It can be divided in two parts, 21 and 21391, that added together give a palindrome (21412).

The spelling of 2121391 in words is "two million, one hundred twenty-one thousand, three hundred ninety-one".