1916821 has 4 divisors (see below), whose sum is σ = 1922944. Its totient is φ = 1910700.

The previous prime is 1916809. The next prime is 1916833. The reversal of 1916821 is 1286191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (1916809) and next prime (1916833).

It is a cyclic number.

It is not a de Polignac number, because 1916821 - 2⁹ = 1916309 is a prime.

It is a Duffinian number.

1916821 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1916821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1916881) 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, 2565 + ... + 3226.

It is an arithmetic number, because the mean of its divisors is an integer number (480736).

2^1916821 is an apocalyptic number.

It is an amenable number.

1916821 is a deficient number, since it is larger than the sum of its proper divisors (6123).

1916821 is an equidigital number, since it uses as much as digits as its factorization.

1916821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6122.

The product of its digits is 864, while the sum is 28.

The square root of 1916821 is about 1384.4930480143. The cubic root of 1916821 is about 124.2206658711.

The spelling of 1916821 in words is "one million, nine hundred sixteen thousand, eight hundred twenty-one".