781038005981 has 2 divisors, whose sum is σ = 781038005982. Its totient is φ = 781038005980.

The previous prime is 781038005941. The next prime is 781038006169. The reversal of 781038005981 is 189500830187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 470917102756 + 310120903225 = 686234^2 + 556885^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-781038005981 is a prime.

It is a super-2 number, since 2×781038005981² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781038005941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390519002990 + 390519002991.

It is an arithmetic number, because the mean of its divisors is an integer number (390519002991).

Almost surely, 2^781038005981 is an apocalyptic number.

It is an amenable number.

781038005981 is a deficient number, since it is larger than the sum of its proper divisors (1).

781038005981 is an equidigital number, since it uses as much as digits as its factorization.

781038005981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 483840, while the sum is 50.

The spelling of 781038005981 in words is "seven hundred eighty-one billion, thirty-eight million, five thousand, nine hundred eighty-one".