221445391 has 2 divisors, whose sum is σ = 221445392. Its totient is φ = 221445390.

The previous prime is 221445377. The next prime is 221445457. The reversal of 221445391 is 193544122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221445391 - 2⁹ = 221444879 is a prime.

It is a super-2 number, since 2×221445391² = 98076122390285762, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221445331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110722695 + 110722696.

It is an arithmetic number, because the mean of its divisors is an integer number (110722696).

Almost surely, 2^221445391 is an apocalyptic number.

221445391 is a deficient number, since it is larger than the sum of its proper divisors (1).

221445391 is an equidigital number, since it uses as much as digits as its factorization.

221445391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 31.

The square root of 221445391 is about 14881.0413278104. The cubic root of 221445391 is about 605.0002422420. Note that the first 3 decimals are identical.

The spelling of 221445391 in words is "two hundred twenty-one million, four hundred forty-five thousand, three hundred ninety-one".