781728671 has 2 divisors, whose sum is σ = 781728672. Its totient is φ = 781728670.

The previous prime is 781728599. The next prime is 781728679. The reversal of 781728671 is 176827187.

It is a strong prime.

It is an emirp because it is prime and its reverse (176827187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 781728671 - 2¹⁸ = 781466527 is a prime.

It is a super-2 number, since 2×781728671² = 1222199430126852482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781728679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390864335 + 390864336.

It is an arithmetic number, because the mean of its divisors is an integer number (390864336).

Almost surely, 2^781728671 is an apocalyptic number.

781728671 is a deficient number, since it is larger than the sum of its proper divisors (1).

781728671 is an equidigital number, since it uses as much as digits as its factorization.

781728671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 263424, while the sum is 47.

The square root of 781728671 is about 27959.4111347146. The cubic root of 781728671 is about 921.1959364213.

The spelling of 781728671 in words is "seven hundred eighty-one million, seven hundred twenty-eight thousand, six hundred seventy-one".