1891397 has 4 divisors (see below), whose sum is σ = 1901196. Its totient is φ = 1881600.

The previous prime is 1891391. The next prime is 1891429. The reversal of 1891397 is 7931981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7931981 = 97 ⋅81773.

It can be written as a sum of positive squares in 2 ways, for example, as 1705636 + 185761 = 1306^2 + 431^2 .

It is a cyclic number.

It is not a de Polignac number, because 1891397 - 2⁴ = 1891381 is a prime.

It is a super-2 number, since 2×1891397² = 7154765223218, which contains 22 as substring.

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 1891397.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1891391) 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, 4604 + ... + 4997.

It is an arithmetic number, because the mean of its divisors is an integer number (475299).

2^1891397 is an apocalyptic number.

It is an amenable number.

1891397 is a deficient number, since it is larger than the sum of its proper divisors (9799).

1891397 is an equidigital number, since it uses as much as digits as its factorization.

1891397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9798.

The product of its digits is 13608, while the sum is 38.

The square root of 1891397 is about 1375.2806986212. The cubic root of 1891397 is about 123.6690141139.

The spelling of 1891397 in words is "one million, eight hundred ninety-one thousand, three hundred ninety-seven".