1938790981 has 2 divisors, whose sum is σ = 1938790982. Its totient is φ = 1938790980.

The previous prime is 1938790979. The next prime is 1938790991. The reversal of 1938790981 is 1890978391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1929844900 + 8946081 = 43930^2 + 2991^2 .

It is a cyclic number.

It is not a de Polignac number, because 1938790981 - 2¹ = 1938790979 is a prime.

It is a super-2 number, since 2×1938790981² = 7517820936013884722, which contains 22 as substring.

Together with 1938790979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1938790991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 969395490 + 969395491.

It is an arithmetic number, because the mean of its divisors is an integer number (969395491).

Almost surely, 2^1938790981 is an apocalyptic number.

It is an amenable number.

1938790981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1938790981 is an equidigital number, since it uses as much as digits as its factorization.

1938790981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 979776, while the sum is 55.

The square root of 1938790981 is about 44031.7042709001. The cubic root of 1938790981 is about 1246.9345645764.

The spelling of 1938790981 in words is "one billion, nine hundred thirty-eight million, seven hundred ninety thousand, nine hundred eighty-one".