221955442091 has 4 divisors (see below), whose sum is σ = 222325986000. Its totient is φ = 221584898184.

The previous prime is 221955442073. The next prime is 221955442097. The reversal of 221955442091 is 190244559122.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221955442091 is a prime.

It is a super-2 number, since 2×221955442091² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221955442097) 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, 185271056 + ... + 185272253.

It is an arithmetic number, because the mean of its divisors is an integer number (55581496500).

Almost surely, 2^221955442091 is an apocalyptic number.

221955442091 is a deficient number, since it is larger than the sum of its proper divisors (370543909).

221955442091 is an equidigital number, since it uses as much as digits as its factorization.

221955442091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 370543908.

The product of its (nonzero) digits is 259200, while the sum is 44.

The spelling of 221955442091 in words is "two hundred twenty-one billion, nine hundred fifty-five million, four hundred forty-two thousand, ninety-one".