221391191 has 8 divisors (see below), whose sum is σ = 261743520. Its totient is φ = 183220128.

The previous prime is 221391167. The next prime is 221391199. The reversal of 221391191 is 191193122.

221391191 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 221391191 - 2¹⁴ = 221374807 is a prime.

It is a super-4 number, since 4×221391191⁴ (a number of 34 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221391199) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 545096 + ... + 545501.

It is an arithmetic number, because the mean of its divisors is an integer number (32717940).

Almost surely, 2^221391191 is an apocalyptic number.

221391191 is a deficient number, since it is larger than the sum of its proper divisors (40352329).

221391191 is a wasteful number, since it uses less digits than its factorization.

221391191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1090633.

The product of its digits is 972, while the sum is 29.

The square root of 221391191 is about 14879.2201072502. The cubic root of 221391191 is about 604.9508791483.

The spelling of 221391191 in words is "two hundred twenty-one million, three hundred ninety-one thousand, one hundred ninety-one".