221971187 has 2 divisors, whose sum is σ = 221971188. Its totient is φ = 221971186.

The previous prime is 221971163. The next prime is 221971199. The reversal of 221971187 is 781179122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221971187 - 2²² = 217776883 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221971187.

It is not a weakly prime, because it can be changed into another prime (221971487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110985593 + 110985594.

It is an arithmetic number, because the mean of its divisors is an integer number (110985594).

Almost surely, 2^221971187 is an apocalyptic number.

221971187 is a deficient number, since it is larger than the sum of its proper divisors (1).

221971187 is an equidigital number, since it uses as much as digits as its factorization.

221971187 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 38.

The square root of 221971187 is about 14898.6974934053. The cubic root of 221971187 is about 605.4786977031.

The spelling of 221971187 in words is "two hundred twenty-one million, nine hundred seventy-one thousand, one hundred eighty-seven".