221212091 has 8 divisors (see below), whose sum is σ = 234276864. Its totient is φ = 208434600.

The previous prime is 221212049. The next prime is 221212093. The reversal of 221212091 is 190212122.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221212091 - 2¹⁸ = 220949947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221212093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70235 + ... + 73316.

It is an arithmetic number, because the mean of its divisors is an integer number (29284608).

Almost surely, 2^221212091 is an apocalyptic number.

221212091 is a deficient number, since it is larger than the sum of its proper divisors (13064773).

221212091 is a wasteful number, since it uses less digits than its factorization.

221212091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143641.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 221212091 is about 14873.2004289595. The cubic root of 221212091 is about 604.7877050375.

The spelling of 221212091 in words is "two hundred twenty-one million, two hundred twelve thousand, ninety-one".