9781920 has 72 divisors (see below), whose sum is σ = 33385716. Its totient is φ = 2608128.

The previous prime is 9781909. The next prime is 9781943. The reversal of 9781920 is 291879.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8928144 + 853776 = 2988^2 + 924^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1957 + ... + 4836.

Almost surely, 2^9781920 is an apocalyptic number.

9781920 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

9781920 is an abundant number, since it is smaller than the sum of its proper divisors (23603796).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9781920 is a wasteful number, since it uses less digits than its factorization.

9781920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6814 (or 6803 counting only the distinct ones).

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

The square root of 9781920 is about 3127.6061133077. The cubic root of 9781920 is about 213.8658139184.

It can be divided in two parts, 9781 and 920, that added together give a palindrome (10701).

The spelling of 9781920 in words is "nine million, seven hundred eighty-one thousand, nine hundred twenty".