1191681 has 6 divisors (see below), whose sum is σ = 1721330. Its totient is φ = 794448.

The previous prime is 1191679. The next prime is 1191691. The reversal of 1191681 is 1861911.

It can be written as a sum of positive squares in only one way, i.e., 1166400 + 25281 = 1080^2 + 159^2 .

It is not a de Polignac number, because 1191681 - 2¹ = 1191679 is a prime.

It is a super-2 number, since 2×1191681² = 2840207211522, which contains 22 as substring.

It is a Duffinian number.

1191681 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1191601) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 66196 + ... + 66213.

2^1191681 is an apocalyptic number.

It is an amenable number.

1191681 is a deficient number, since it is larger than the sum of its proper divisors (529649).

1191681 is a wasteful number, since it uses less digits than its factorization.

1191681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132415 (or 132412 counting only the distinct ones).

The product of its digits is 432, while the sum is 27.

The square root of 1191681 is about 1091.6414246446. The cubic root of 1191681 is about 106.0197245838.

The spelling of 1191681 in words is "one million, one hundred ninety-one thousand, six hundred eighty-one".