781041581 has 2 divisors, whose sum is σ = 781041582. Its totient is φ = 781041580.

The previous prime is 781041577. The next prime is 781041589. The reversal of 781041581 is 185140187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 531717481 + 249324100 = 23059^2 + 15790^2 .

It is a cyclic number.

It is not a de Polignac number, because 781041581 - 2² = 781041577 is a prime.

It is a super-2 number, since 2×781041581² = 1220051902501959122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781041589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390520790 + 390520791.

It is an arithmetic number, because the mean of its divisors is an integer number (390520791).

Almost surely, 2^781041581 is an apocalyptic number.

It is an amenable number.

781041581 is a deficient number, since it is larger than the sum of its proper divisors (1).

781041581 is an equidigital number, since it uses as much as digits as its factorization.

781041581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8960, while the sum is 35.

The square root of 781041581 is about 27947.1211576434. The cubic root of 781041581 is about 920.9259663454.

The spelling of 781041581 in words is "seven hundred eighty-one million, forty-one thousand, five hundred eighty-one".