9827215555921 has 9 divisors (see below), whose sum is σ = 9963911074779. Its totient is φ = 9692370456336.

The previous prime is 9827215555891. The next prime is 9827215555967. The reversal of 9827215555921 is 1295555127289.

The square root of 9827215555921 is 3134839.

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

It can be written as a sum of positive squares in only one way, i.e., 5578406278225 + 4248809277696 = 2361865^2 + 2061264^2 .

It is not a de Polignac number, because 9827215555921 - 2⁵ = 9827215555889 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9827215555921.

It is not an unprimeable number, because it can be changed into a prime (9827215555991) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 228821776 + ... + 228864718.

It is an arithmetic number, because the mean of its divisors is an integer number (1107101230531).

Almost surely, 2^{9827215555921} is an apocalyptic number.

9827215555921 is the 3134839-th square number.

9827215555921 is the 1567420-th centered octagonal number.

It is an amenable number.

9827215555921 is a deficient number, since it is larger than the sum of its proper divisors (136695518858).

9827215555921 is an frugal number, since it uses more digits than its factorization.

9827215555921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86032 (or 43016 counting only the distinct ones).

The product of its digits is 22680000, while the sum is 61.

The spelling of 9827215555921 in words is "nine trillion, eight hundred twenty-seven billion, two hundred fifteen million, five hundred fifty-five thousand, nine hundred twenty-one".