99911221 has 4 divisors (see below), whose sum is σ = 101176000. Its totient is φ = 98646444.

The previous prime is 99911197. The next prime is 99911263. The reversal of 99911221 is 12211999.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12211999 = 829 ⋅14731.

It is a cyclic number.

It is not a de Polignac number, because 99911221 - 2⁷ = 99911093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99911621) 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, 632271 + ... + 632428.

It is an arithmetic number, because the mean of its divisors is an integer number (25294000).

Almost surely, 2^99911221 is an apocalyptic number.

It is an amenable number.

99911221 is a deficient number, since it is larger than the sum of its proper divisors (1264779).

99911221 is a wasteful number, since it uses less digits than its factorization.

99911221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1264778.

The product of its digits is 2916, while the sum is 34.

The square root of 99911221 is about 9995.5600643486. The cubic root of 99911221 is about 464.0214841544.

The spelling of 99911221 in words is "ninety-nine million, nine hundred eleven thousand, two hundred twenty-one".