221406643 has 2 divisors, whose sum is σ = 221406644. Its totient is φ = 221406642.

The previous prime is 221406629. The next prime is 221406667. The reversal of 221406643 is 346604122.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221406643 is a prime.

It is not a weakly prime, because it can be changed into another prime (221406673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110703321 + 110703322.

It is an arithmetic number, because the mean of its divisors is an integer number (110703322).

Almost surely, 2^221406643 is an apocalyptic number.

221406643 is a deficient number, since it is larger than the sum of its proper divisors (1).

221406643 is an equidigital number, since it uses as much as digits as its factorization.

221406643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 221406643 is about 14879.7393458353. The cubic root of 221406643 is about 604.9649530048.

The spelling of 221406643 in words is "two hundred twenty-one million, four hundred six thousand, six hundred forty-three".