9988857581 has 2 divisors, whose sum is σ = 9988857582. Its totient is φ = 9988857580.

The previous prime is 9988857577. The next prime is 9988857607. The reversal of 9988857581 is 1857588899.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9946072900 + 42784681 = 99730^2 + 6541^2 .

It is a cyclic number.

It is not a de Polignac number, because 9988857581 - 2² = 9988857577 is a prime.

It is a super-2 number, since 2×9988857581² (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 (9988157581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4994428790 + 4994428791.

It is an arithmetic number, because the mean of its divisors is an integer number (4994428791).

Almost surely, 2^9988857581 is an apocalyptic number.

It is an amenable number.

9988857581 is a deficient number, since it is larger than the sum of its proper divisors (1).

9988857581 is an equidigital number, since it uses as much as digits as its factorization.

9988857581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 58060800, while the sum is 68.

The square root of 9988857581 is about 99944.2723771603. The cubic root of 9988857581 is about 2153.6342055129.

The spelling of 9988857581 in words is "nine billion, nine hundred eighty-eight million, eight hundred fifty-seven thousand, five hundred eighty-one".