1091581972 has 12 divisors (see below), whose sum is σ = 2057212276. Its totient is φ = 503807040.

The previous prime is 1091581963. The next prime is 1091581979. The reversal of 1091581972 is 2791851901.

It can be written as a sum of positive squares in 2 ways, for example, as 737991556 + 353590416 = 27166^2 + 18804^2 .

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1091581979) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10495929 + ... + 10496032.

Almost surely, 2^1091581972 is an apocalyptic number.

It is an amenable number.

1091581972 is a deficient number, since it is larger than the sum of its proper divisors (965630304).

1091581972 is a wasteful number, since it uses less digits than its factorization.

1091581972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20991978 (or 20991976 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 43.

The square root of 1091581972 is about 33039.0976269026. The cubic root of 1091581972 is about 1029.6401080287.

The spelling of 1091581972 in words is "one billion, ninety-one million, five hundred eighty-one thousand, nine hundred seventy-two".