1281121591 has 6 divisors (see below), whose sum is σ = 1297660560. Its totient is φ = 1264590756.

The previous prime is 1281121561. The next prime is 1281121609. The reversal of 1281121591 is 1951211821.

It is a de Polignac number, because none of the positive numbers 2^k-1281121591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1281121561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 316120 + ... + 320146.

It is an arithmetic number, because the mean of its divisors is an integer number (216276760).

Almost surely, 2^1281121591 is an apocalyptic number.

1281121591 is a deficient number, since it is larger than the sum of its proper divisors (16538969).

1281121591 is an frugal number, since it uses more digits than its factorization.

1281121591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8133 (or 4106 counting only the distinct ones).

The product of its digits is 1440, while the sum is 31.

The square root of 1281121591 is about 35792.7589185299. The cubic root of 1281121591 is about 1086.0840859683.

The spelling of 1281121591 in words is "one billion, two hundred eighty-one million, one hundred twenty-one thousand, five hundred ninety-one".