1091971 has 8 divisors (see below), whose sum is σ = 1149984. Its totient is φ = 1034880.

The previous prime is 1091957. The next prime is 1091983. The reversal of 1091971 is 1791901.

1091971 = 131² + 132² + ... + 176².

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1091971 - 2⁵ = 1091939 is a prime.

It is a Duffinian number.

1091971 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1091071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4411 + ... + 4651.

It is an arithmetic number, because the mean of its divisors is an integer number (143748).

2^1091971 is an apocalyptic number.

1091971 is a deficient number, since it is larger than the sum of its proper divisors (58013).

1091971 is a wasteful number, since it uses less digits than its factorization.

1091971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 461.

The product of its (nonzero) digits is 567, while the sum is 28.

The square root of 1091971 is about 1044.9741623600. The cubic root of 1091971 is about 102.9762411031.

It can be divided in two parts, 109 and 1971, that added together give a triangular number (2080 = T₆₄).

The spelling of 1091971 in words is "one million, ninety-one thousand, nine hundred seventy-one".