1125181921 has 4 divisors (see below), whose sum is σ = 1161478144. Its totient is φ = 1088885700.

The previous prime is 1125181913. The next prime is 1125181949. The reversal of 1125181921 is 1291815211.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1291815211 = 15193 ⋅85027.

It is a cyclic number.

It is not a de Polignac number, because 1125181921 - 2³ = 1125181913 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 36296191 = 1125181921 / (1 + 1 + 2 + 5 + 1 + 8 + 1 + 9 + 2 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1125181021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18148065 + ... + 18148126.

It is an arithmetic number, because the mean of its divisors is an integer number (290369536).

Almost surely, 2^1125181921 is an apocalyptic number.

It is an amenable number.

1125181921 is a deficient number, since it is larger than the sum of its proper divisors (36296223).

1125181921 is an equidigital number, since it uses as much as digits as its factorization.

1125181921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36296222.

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

The square root of 1125181921 is about 33543.7314710215. The cubic root of 1125181921 is about 1040.0979693828.

The spelling of 1125181921 in words is "one billion, one hundred twenty-five million, one hundred eighty-one thousand, nine hundred twenty-one".