9891771642 has 12 divisors (see below), whose sum is σ = 21432171930. Its totient is φ = 3297257208.

The previous prime is 9891771601. The next prime is 9891771649. The reversal of 9891771642 is 2461771989.

It can be written as a sum of positive squares in only one way, i.e., 9733992921 + 157778721 = 98661^2 + 12561^2 .

It is not an unprimeable number, because it can be changed into a prime (9891771649) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 274771417 + ... + 274771452.

Almost surely, 2^9891771642 is an apocalyptic number.

9891771642 is an abundant number, since it is smaller than the sum of its proper divisors (11540400288).

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

9891771642 is a wasteful number, since it uses less digits than its factorization.

9891771642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549542877 (or 549542874 counting only the distinct ones).

The product of its digits is 1524096, while the sum is 54.

The square root of 9891771642 is about 99457.3860605636. The cubic root of 9891771642 is about 2146.6341162404.

The spelling of 9891771642 in words is "nine billion, eight hundred ninety-one million, seven hundred seventy-one thousand, six hundred forty-two".