219985921 has 4 divisors (see below), whose sum is σ = 220780372. Its totient is φ = 219191472.

The previous prime is 219985919. The next prime is 219985937. The reversal of 219985921 is 129589912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 92544400 + 127441521 = 9620^2 + 11289^2 .

It is a cyclic number.

It is not a de Polignac number, because 219985921 - 2¹ = 219985919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (219985981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 396810 + ... + 397363.

It is an arithmetic number, because the mean of its divisors is an integer number (55195093).

Almost surely, 2^219985921 is an apocalyptic number.

It is an amenable number.

219985921 is a deficient number, since it is larger than the sum of its proper divisors (794451).

219985921 is an equidigital number, since it uses as much as digits as its factorization.

219985921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 794450.

The product of its digits is 116640, while the sum is 46.

The square root of 219985921 is about 14831.9223636048. The cubic root of 219985921 is about 603.6681957902.

The spelling of 219985921 in words is "two hundred nineteen million, nine hundred eighty-five thousand, nine hundred twenty-one".