99991220 has 24 divisors (see below), whose sum is σ = 239979264. Its totient is φ = 34282656.

The previous prime is 99991207. The next prime is 99991237. The reversal of 99991220 is 2219999.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 356972 + ... + 357251.

It is an arithmetic number, because the mean of its divisors is an integer number (9999136).

Almost surely, 2^99991220 is an apocalyptic number.

It is an amenable number.

99991220 is an abundant number, since it is smaller than the sum of its proper divisors (139988044).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

99991220 is a wasteful number, since it uses less digits than its factorization.

99991220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714239 (or 714237 counting only the distinct ones).

The product of its (nonzero) digits is 26244, while the sum is 41.

The square root of 99991220 is about 9999.5609903635. The cubic root of 99991220 is about 464.1452985804.

The spelling of 99991220 in words is "ninety-nine million, nine hundred ninety-one thousand, two hundred twenty".