1921399 has 4 divisors (see below), whose sum is σ = 1939464. Its totient is φ = 1903336.

The previous prime is 1921393. The next prime is 1921417. The reversal of 1921399 is 9931291.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1921399 is a prime.

It is a Duffinian number.

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, 8872 + ... + 9085.

It is an arithmetic number, because the mean of its divisors is an integer number (484866).

2^1921399 is an apocalyptic number.

1921399 is a deficient number, since it is larger than the sum of its proper divisors (18065).

1921399 is a wasteful number, since it uses less digits than its factorization.

1921399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18064.

The product of its digits is 4374, while the sum is 34.

The square root of 1921399 is about 1386.1453747713. The cubic root of 1921399 is about 124.3194805360.

The spelling of 1921399 in words is "one million, nine hundred twenty-one thousand, three hundred ninety-nine".