1981549013 has 2 divisors, whose sum is σ = 1981549014. Its totient is φ = 1981549012.

The previous prime is 1981548973. The next prime is 1981549027. The reversal of 1981549013 is 3109451891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1311671089 + 669877924 = 36217^2 + 25882^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981549013 - 2⁸ = 1981548757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1981549513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990774506 + 990774507.

It is an arithmetic number, because the mean of its divisors is an integer number (990774507).

Almost surely, 2^1981549013 is an apocalyptic number.

It is an amenable number.

1981549013 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981549013 is an equidigital number, since it uses as much as digits as its factorization.

1981549013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 1981549013 is about 44514.5932588404. The cubic root of 1981549013 is about 1256.0346093500.

The spelling of 1981549013 in words is "one billion, nine hundred eighty-one million, five hundred forty-nine thousand, thirteen".