1115531781 has 32 divisors (see below), whose sum is σ = 1926973440. Its totient is φ = 557440704.

The previous prime is 1115531749. The next prime is 1115531797. The reversal of 1115531781 is 1871355111.

It is not a de Polignac number, because 1115531781 - 2⁵ = 1115531749 is a prime.

It is a super-2 number, since 2×1115531781² = 2488822308842063922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1115531741) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 102345 + ... + 112718.

It is an arithmetic number, because the mean of its divisors is an integer number (60217920).

Almost surely, 2^1115531781 is an apocalyptic number.

It is an amenable number.

1115531781 is a deficient number, since it is larger than the sum of its proper divisors (811441659).

1115531781 is a wasteful number, since it uses less digits than its factorization.

1115531781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215105.

The product of its digits is 4200, while the sum is 33.

The square root of 1115531781 is about 33399.5775572087. The cubic root of 1115531781 is about 1037.1159559087.

Adding to 1115531781 its reverse (1871355111), we get a palindrome (2986886892).

The spelling of 1115531781 in words is "one billion, one hundred fifteen million, five hundred thirty-one thousand, seven hundred eighty-one".