9915955379521 has 9 divisors (see below), whose sum is σ = 10533615003561. Its totient is φ = 9332613503232.

The previous prime is 9915955379479. The next prime is 9915955379567. The reversal of 9915955379521 is 1259735595199.

The square root of 9915955379521 is 3148961.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1745276145921 + 8170679233600 = 1321089^2 + 2858440^2 .

It is not a de Polignac number, because 9915955379521 - 2²¹ = 9915953282369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9915955371521) 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, 53439721 + ... + 53624953.

Almost surely, 2^{9915955379521} is an apocalyptic number.

9915955379521 is the 3148961-st square number.

9915955379521 is the 1574481-st centered octagonal number.

It is an amenable number.

9915955379521 is a deficient number, since it is larger than the sum of its proper divisors (617659624040).

9915955379521 is an frugal number, since it uses more digits than its factorization.

9915955379521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370500 (or 185250 counting only the distinct ones).

The product of its digits is 172226250, while the sum is 70.

The spelling of 9915955379521 in words is "nine trillion, nine hundred fifteen billion, nine hundred fifty-five million, three hundred seventy-nine thousand, five hundred twenty-one".