1911397 has 4 divisors (see below), whose sum is σ = 1914220. Its totient is φ = 1908576.

The previous prime is 1911373. The next prime is 1911401. The reversal of 1911397 is 7931191.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7931191 = 2221 ⋅3571.

It can be written as a sum of positive squares in 2 ways, for example, as 408321 + 1503076 = 639^2 + 1226^2 .

It is a 3-Lehmer number, since φ(1911397) divides (1911397-1)³.

It is a cyclic number.

It is not a de Polignac number, because 1911397 - 2⁷ = 1911269 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1911317) 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, 283 + ... + 1975.

It is an arithmetic number, because the mean of its divisors is an integer number (478555).

2^1911397 is an apocalyptic number.

1911397 is the 1129-th pentagonal number.

It is an amenable number.

1911397 is a deficient number, since it is larger than the sum of its proper divisors (2823).

1911397 is a wasteful number, since it uses less digits than its factorization.

1911397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2822.

The product of its digits is 1701, while the sum is 31.

The square root of 1911397 is about 1382.5328205869. The cubic root of 1911397 is about 124.1033867208.

The spelling of 1911397 in words is "one million, nine hundred eleven thousand, three hundred ninety-seven".