1211142981 has 4 divisors (see below), whose sum is σ = 1614857312. Its totient is φ = 807428652.

The previous prime is 1211142971. The next prime is 1211142991. The reversal of 1211142981 is 1892411121.

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.

It is an interprime number because it is at equal distance from previous prime (1211142971) and next prime (1211142991).

It is not a de Polignac number, because 1211142981 - 2¹³ = 1211134789 is a prime.

It is a super-2 number, since 2×1211142981² = 2933734640851132722, 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 (1211142971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 201857161 + ... + 201857166.

It is an arithmetic number, because the mean of its divisors is an integer number (403714328).

Almost surely, 2^1211142981 is an apocalyptic number.

It is an amenable number.

1211142981 is a deficient number, since it is larger than the sum of its proper divisors (403714331).

1211142981 is an equidigital number, since it uses as much as digits as its factorization.

1211142981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403714330.

The product of its digits is 1152, while the sum is 30.

The square root of 1211142981 is about 34801.4795806155. The cubic root of 1211142981 is about 1065.9376582020.

The spelling of 1211142981 in words is "one billion, two hundred eleven million, one hundred forty-two thousand, nine hundred eighty-one".