221864639 has 2 divisors, whose sum is σ = 221864640. Its totient is φ = 221864638.

The previous prime is 221864633. The next prime is 221864651. The reversal of 221864639 is 936468122.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221864639 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221864596 and 221864605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221864633) 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, 110932319 + 110932320.

It is an arithmetic number, because the mean of its divisors is an integer number (110932320).

Almost surely, 2^221864639 is an apocalyptic number.

221864639 is a deficient number, since it is larger than the sum of its proper divisors (1).

221864639 is an equidigital number, since it uses as much as digits as its factorization.

221864639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 41.

The square root of 221864639 is about 14895.1213153838. The cubic root of 221864639 is about 605.3818039424.

The spelling of 221864639 in words is "two hundred twenty-one million, eight hundred sixty-four thousand, six hundred thirty-nine".