9728918581 has 2 divisors, whose sum is σ = 9728918582. Its totient is φ = 9728918580.

The previous prime is 9728918569. The next prime is 9728918599. The reversal of 9728918581 is 1858198279.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5284563025 + 4444355556 = 72695^2 + 66666^2 .

It is a cyclic number.

It is not a de Polignac number, because 9728918581 - 2¹⁵ = 9728885813 is a prime.

It is a super-2 number, since 2×9728918581² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9728918681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4864459290 + 4864459291.

It is an arithmetic number, because the mean of its divisors is an integer number (4864459291).

Almost surely, 2^9728918581 is an apocalyptic number.

It is an amenable number.

9728918581 is a deficient number, since it is larger than the sum of its proper divisors (1).

9728918581 is an equidigital number, since it uses as much as digits as its factorization.

9728918581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2903040, while the sum is 58.

The square root of 9728918581 is about 98635.2806099319. The cubic root of 9728918581 is about 2134.7885082842.

The spelling of 9728918581 in words is "nine billion, seven hundred twenty-eight million, nine hundred eighteen thousand, five hundred eighty-one".