1121381981 has 4 divisors (see below), whose sum is σ = 1136743452. Its totient is φ = 1106020512.

The previous prime is 1121381959. The next prime is 1121382007. The reversal of 1121381981 is 1891831211.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1891831211 = 29 ⋅65235559.

It can be written as a sum of positive squares in 2 ways, for example, as 426216025 + 695165956 = 20645^2 + 26366^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1121381981 is a prime.

It is a super-2 number, since 2×1121381981² = 2514995094622968722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1121383981) 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, 7680626 + ... + 7680771.

It is an arithmetic number, because the mean of its divisors is an integer number (284185863).

Almost surely, 2^1121381981 is an apocalyptic number.

It is an amenable number.

1121381981 is a deficient number, since it is larger than the sum of its proper divisors (15361471).

1121381981 is an equidigital number, since it uses as much as digits as its factorization.

1121381981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15361470.

The product of its digits is 3456, while the sum is 35.

The square root of 1121381981 is about 33487.0419864162. The cubic root of 1121381981 is about 1038.9257833896.

The spelling of 1121381981 in words is "one billion, one hundred twenty-one million, three hundred eighty-one thousand, nine hundred eighty-one".