1156271991 has 32 divisors (see below), whose sum is σ = 1791590400. Its totient is φ = 649659360.

The previous prime is 1156271989. The next prime is 1156272001. The reversal of 1156271991 is 1991726511.

It is a happy number.

It is not a de Polignac number, because 1156271991 - 2¹ = 1156271989 is a prime.

It is a super-2 number, since 2×1156271991² = 2673929834342208162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1156271971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 713380 + ... + 714998.

It is an arithmetic number, because the mean of its divisors is an integer number (55987200).

Almost surely, 2^1156271991 is an apocalyptic number.

1156271991 is a deficient number, since it is larger than the sum of its proper divisors (635318409).

1156271991 is a wasteful number, since it uses less digits than its factorization.

1156271991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2179.

The product of its digits is 34020, while the sum is 42.

The square root of 1156271991 is about 34003.9996323962. Note that the first 3 decimals coincide. The cubic root of 1156271991 is about 1049.5907675084.

The spelling of 1156271991 in words is "one billion, one hundred fifty-six million, two hundred seventy-one thousand, nine hundred ninety-one".