9999121011221 has 4 divisors (see below), whose sum is σ = 10343918287500. Its totient is φ = 9654323734944.

The previous prime is 9999121011199. The next prime is 9999121011247. The reversal of 9999121011221 is 1221101219999.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8111753356996 + 1887367654225 = 2848114^2 + 1373815^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9999121011221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9999121091221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 172398638096 + ... + 172398638153.

It is an arithmetic number, because the mean of its divisors is an integer number (2585979571875).

Almost surely, 2^{9999121011221} is an apocalyptic number.

It is an amenable number.

9999121011221 is a deficient number, since it is larger than the sum of its proper divisors (344797276279).

9999121011221 is a wasteful number, since it uses less digits than its factorization.

9999121011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344797276278.

The product of its (nonzero) digits is 52488, while the sum is 47.

The spelling of 9999121011221 in words is "nine trillion, nine hundred ninety-nine billion, one hundred twenty-one million, eleven thousand, two hundred twenty-one".