978781 has 4 divisors (see below), whose sum is σ = 985500. Its totient is φ = 972064.

The previous prime is 978773. The next prime is 978797. The reversal of 978781 is 187879.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 187879 = 89 ⋅2111.

It can be written as a sum of positive squares in 2 ways, for example, as 502681 + 476100 = 709^2 + 690^2 .

It is a cyclic number.

It is not a de Polignac number, because 978781 - 2³ = 978773 is a prime.

It is a super-2 number, since 2×978781² = 1916024491922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (978181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3136 + ... + 3433.

It is an arithmetic number, because the mean of its divisors is an integer number (246375).

2⁹⁷⁸⁷⁸¹ is an apocalyptic number.

It is an amenable number.

978781 is a deficient number, since it is larger than the sum of its proper divisors (6719).

978781 is a wasteful number, since it uses less digits than its factorization.

978781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6718.

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

The square root of 978781 is about 989.3336141060. Note that the first 3 decimals coincide. The cubic root of 978781 is about 99.2876374458.

It can be divided in two parts, 97878 and 1, that added together give a palindrome (97879).

The spelling of 978781 in words is "nine hundred seventy-eight thousand, seven hundred eighty-one".