9877721217 has 32 divisors (see below), whose sum is σ = 16215214848. Its totient is φ = 5208420096.

The previous prime is 9877721167. The next prime is 9877721237. The reversal of 9877721217 is 7121277789.

It is not a de Polignac number, because 9877721217 - 2¹⁴ = 9877704833 is a prime.

It is a super-2 number, since 2×9877721217² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 9877721217.

It is not an unprimeable number, because it can be changed into a prime (9877721237) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1222563 + ... + 1230615.

It is an arithmetic number, because the mean of its divisors is an integer number (506725464).

Almost surely, 2^9877721217 is an apocalyptic number.

It is an amenable number.

9877721217 is a deficient number, since it is larger than the sum of its proper divisors (6337493631).

9877721217 is a wasteful number, since it uses less digits than its factorization.

9877721217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12569.

The product of its digits is 691488, while the sum is 51.

The square root of 9877721217 is about 99386.7255572896. The cubic root of 9877721217 is about 2145.6172639021.

The spelling of 9877721217 in words is "nine billion, eight hundred seventy-seven million, seven hundred twenty-one thousand, two hundred seventeen".