781897 has 2 divisors, whose sum is σ = 781898. Its totient is φ = 781896.

The previous prime is 781889. The next prime is 781919. The reversal of 781897 is 798187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 781456 + 441 = 884^2 + 21^2 .

It is a cyclic number.

It is not a de Polignac number, because 781897 - 2³ = 781889 is a prime.

It is a super-2 number, since 2×781897² = 1222725837218, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390948 + 390949.

It is an arithmetic number, because the mean of its divisors is an integer number (390949).

2⁷⁸¹⁸⁹⁷ is an apocalyptic number.

It is an amenable number.

781897 is a deficient number, since it is larger than the sum of its proper divisors (1).

781897 is an equidigital number, since it uses as much as digits as its factorization.

781897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28224, while the sum is 40.

The square root of 781897 is about 884.2493992082. The cubic root of 781897 is about 92.1262051800.

Subtracting 781897 from its reverse (798187), we obtain a triangular number (16290 = T₁₈₀).

The spelling of 781897 in words is "seven hundred eighty-one thousand, eight hundred ninety-seven".