9920781 has 12 divisors (see below), whose sum is σ = 15432508. Its totient is φ = 6105024.

The previous prime is 9920777. The next prime is 9920783. The reversal of 9920781 is 1870299.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 5447556 + 4473225 = 2334^2 + 2115^2 .

It is not a de Polignac number, because 9920781 - 2² = 9920777 is a prime.

It is a super-2 number, since 2×9920781² = 196843791299922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9920783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42280 + ... + 42513.

Almost surely, 2^9920781 is an apocalyptic number.

It is an amenable number.

9920781 is a deficient number, since it is larger than the sum of its proper divisors (5511727).

9920781 is a wasteful number, since it uses less digits than its factorization.

9920781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84812 (or 84809 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 9920781 is about 3149.7271310385. The cubic root of 9920781 is about 214.8730528754.

It can be divided in two parts, 9920 and 781, that added together give a palindrome (10701).

The spelling of 9920781 in words is "nine million, nine hundred twenty thousand, seven hundred eighty-one".