1981962121 has 2 divisors, whose sum is σ = 1981962122. Its totient is φ = 1981962120.

The previous prime is 1981962107. The next prime is 1981962139. The reversal of 1981962121 is 1212691891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1965680896 + 16281225 = 44336^2 + 4035^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981962121 - 2¹⁵ = 1981929353 is a prime.

It is not a weakly prime, because it can be changed into another prime (1981962421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990981060 + 990981061.

It is an arithmetic number, because the mean of its divisors is an integer number (990981061).

Almost surely, 2^1981962121 is an apocalyptic number.

It is an amenable number.

1981962121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981962121 is an equidigital number, since it uses as much as digits as its factorization.

1981962121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 40.

The square root of 1981962121 is about 44519.2331582654. The cubic root of 1981962121 is about 1256.1218881889.

The spelling of 1981962121 in words is "one billion, nine hundred eighty-one million, nine hundred sixty-two thousand, one hundred twenty-one".