221143991 has 2 divisors, whose sum is σ = 221143992. Its totient is φ = 221143990.

The previous prime is 221143981. The next prime is 221144003. The reversal of 221143991 is 199341122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221143991 - 2⁶ = 221143927 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221143921) 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, 110571995 + 110571996.

It is an arithmetic number, because the mean of its divisors is an integer number (110571996).

Almost surely, 2^221143991 is an apocalyptic number.

221143991 is a deficient number, since it is larger than the sum of its proper divisors (1).

221143991 is an equidigital number, since it uses as much as digits as its factorization.

221143991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 32.

The square root of 221143991 is about 14870.9109001433. The cubic root of 221143991 is about 604.7256374992.

The spelling of 221143991 in words is "two hundred twenty-one million, one hundred forty-three thousand, nine hundred ninety-one".