781388897 has 4 divisors (see below), whose sum is σ = 781594116. Its totient is φ = 781183680.

The previous prime is 781388891. The next prime is 781388983. The reversal of 781388897 is 798883187.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 798883187 = 59 ⋅13540393.

It can be written as a sum of positive squares in 2 ways, for example, as 366492736 + 414896161 = 19144^2 + 20369^2 .

It is a cyclic number.

It is not a de Polignac number, because 781388897 - 2¹² = 781384801 is a prime.

It is a super-2 number, since 2×781388897² = 1221137216709753218, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (781388891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96788 + ... + 104549.

It is an arithmetic number, because the mean of its divisors is an integer number (195398529).

Almost surely, 2^781388897 is an apocalyptic number.

It is an amenable number.

781388897 is a deficient number, since it is larger than the sum of its proper divisors (205219).

781388897 is a wasteful number, since it uses less digits than its factorization.

781388897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205218.

The product of its digits is 5419008, while the sum is 59.

The square root of 781388897 is about 27953.3342733921. The cubic root of 781388897 is about 921.0624528576.

The spelling of 781388897 in words is "seven hundred eighty-one million, three hundred eighty-eight thousand, eight hundred ninety-seven".