1191981 has 16 divisors (see below), whose sum is σ = 1875968. Its totient is φ = 658800.

The previous prime is 1191979. The next prime is 1191991. The reversal of 1191981 is 1891911.

It is a happy number.

It is not a de Polignac number, because 1191981 - 2¹ = 1191979 is a prime.

It is a super-2 number, since 2×1191981² = 2841637408722, which contains 22 as substring.

It is a Duffinian number.

1191981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1191941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 265 + ... + 1566.

It is an arithmetic number, because the mean of its divisors is an integer number (117248).

2^1191981 is an apocalyptic number.

It is an amenable number.

1191981 is a deficient number, since it is larger than the sum of its proper divisors (683987).

1191981 is a wasteful number, since it uses less digits than its factorization.

1191981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1872.

The product of its digits is 648, while the sum is 30.

The square root of 1191981 is about 1091.7788237551. The cubic root of 1191981 is about 106.0286204905.

The spelling of 1191981 in words is "one million, one hundred ninety-one thousand, nine hundred eighty-one".