1921817 has 4 divisors (see below), whose sum is σ = 1973796. Its totient is φ = 1869840.

The previous prime is 1921813. The next prime is 1921819. The reversal of 1921817 is 7181291.

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

It can be written as a sum of positive squares in 2 ways, for example, as 817216 + 1104601 = 904^2 + 1051^2 .

It is a cyclic number.

It is not a de Polignac number, because 1921817 - 2² = 1921813 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 1921817.

It is not an unprimeable number, because it can be changed into a prime (1921813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25934 + ... + 26007.

It is an arithmetic number, because the mean of its divisors is an integer number (493449).

2^1921817 is an apocalyptic number.

It is an amenable number.

1921817 is a deficient number, since it is larger than the sum of its proper divisors (51979).

1921817 is an equidigital number, since it uses as much as digits as its factorization.

1921817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51978.

The product of its digits is 1008, while the sum is 29.

The square root of 1921817 is about 1386.2961444078. The cubic root of 1921817 is about 124.3284951091.

The spelling of 1921817 in words is "one million, nine hundred twenty-one thousand, eight hundred seventeen".