9971819881 has 3 divisors (see below), whose sum is σ = 9971919741. Its totient is φ = 9971720022.

The previous prime is 9971819861. The next prime is 9971819903. The reversal of 9971819881 is 1889181799.

It is a happy number.

The square root of 9971819881 is 99859.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 9971819881 - 2⁵ = 9971819849 is a prime.

It is a super-2 number, since 2×9971819881² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9971819861) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 49930 + ... + 149788.

It is an arithmetic number, because the mean of its divisors is an integer number (3323973247).

Almost surely, 2^9971819881 is an apocalyptic number.

9971819881 is the 99859-th square number.

9971819881 is the 49930-th centered octagonal number.

It is an amenable number.

9971819881 is a deficient number, since it is larger than the sum of its proper divisors (99860).

9971819881 is an frugal number, since it uses more digits than its factorization.

9971819881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199718 (or 99859 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 61.

The cubic root of 9971819881 is about 2152.4090452101.

The spelling of 9971819881 in words is "nine billion, nine hundred seventy-one million, eight hundred nineteen thousand, eight hundred eighty-one".