9981779640 has 256 divisors, whose sum is σ = 35392896000. Its totient is φ = 2204651520.

The previous prime is 9981779623. The next prime is 9981779657. The reversal of 9981779640 is 469771899.

It is an interprime number because it is at equal distance from previous prime (9981779623) and next prime (9981779657).

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3752631 + ... + 3755289.

It is an arithmetic number, because the mean of its divisors is an integer number (138253500).

Almost surely, 2^9981779640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9981779640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17696448000).

9981779640 is an abundant number, since it is smaller than the sum of its proper divisors (25411116360).

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

9981779640 is a wasteful number, since it uses less digits than its factorization.

9981779640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2830 (or 2826 counting only the distinct ones).

The product of its (nonzero) digits is 6858432, while the sum is 60.

The square root of 9981779640 is about 99908.8566644619. The cubic root of 9981779640 is about 2153.1254086687.

The spelling of 9981779640 in words is "nine billion, nine hundred eighty-one million, seven hundred seventy-nine thousand, six hundred forty".