1921391 has 4 divisors (see below), whose sum is σ = 2034432. Its totient is φ = 1808352.

The previous prime is 1921363. The next prime is 1921393. The reversal of 1921391 is 1931291.

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 1921391 - 2⁶ = 1921327 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1921391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1921393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56495 + ... + 56528.

It is an arithmetic number, because the mean of its divisors is an integer number (508608).

2^1921391 is an apocalyptic number.

1921391 is a deficient number, since it is larger than the sum of its proper divisors (113041).

1921391 is a wasteful number, since it uses less digits than its factorization.

1921391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113040.

The product of its digits is 486, while the sum is 26.

The square root of 1921391 is about 1386.1424890681. The cubic root of 1921391 is about 124.3193079955.

The spelling of 1921391 in words is "one million, nine hundred twenty-one thousand, three hundred ninety-one".