9912781 has 4 divisors (see below), whose sum is σ = 10180732. Its totient is φ = 9644832.

The previous prime is 9912779. The next prime is 9912803. The reversal of 9912781 is 1872199.

9912781 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4691556 + 5221225 = 2166^2 + 2285^2 .

It is a cyclic number.

It is not a de Polignac number, because 9912781 - 2¹ = 9912779 is a prime.

It is a super-2 number, since 2×9912781² = 196526454307922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 267913 = 9912781 / (9 + 9 + 1 + 2 + 7 + 8 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9912781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9912761) 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, 133920 + ... + 133993.

It is an arithmetic number, because the mean of its divisors is an integer number (2545183).

Almost surely, 2^9912781 is an apocalyptic number.

It is an amenable number.

9912781 is a deficient number, since it is larger than the sum of its proper divisors (267951).

9912781 is a wasteful number, since it uses less digits than its factorization.

9912781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267950.

The product of its digits is 9072, while the sum is 37.

The square root of 9912781 is about 3148.4569236374. The cubic root of 9912781 is about 214.8152803175.

It can be divided in two parts, 99 and 12781, that added together give a triangular number (12880 = T₁₆₀).

The spelling of 9912781 in words is "nine million, nine hundred twelve thousand, seven hundred eighty-one".