221664511 has 2 divisors, whose sum is σ = 221664512. Its totient is φ = 221664510.

The previous prime is 221664467. The next prime is 221664563. The reversal of 221664511 is 115466122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221664511 - 2⁷ = 221664383 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221664511.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221664571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110832255 + 110832256.

It is an arithmetic number, because the mean of its divisors is an integer number (110832256).

Almost surely, 2^221664511 is an apocalyptic number.

221664511 is a deficient number, since it is larger than the sum of its proper divisors (1).

221664511 is an equidigital number, since it uses as much as digits as its factorization.

221664511 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 28.

The square root of 221664511 is about 14888.4018954353. The cubic root of 221664511 is about 605.1997255116.

The spelling of 221664511 in words is "two hundred twenty-one million, six hundred sixty-four thousand, five hundred eleven".