219920821 has 4 divisors (see below), whose sum is σ = 220255200. Its totient is φ = 219586444.

The previous prime is 219920809. The next prime is 219920893. The reversal of 219920821 is 128029912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 219920821 - 2¹¹ = 219918773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (219920221) 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 in 3 ways as a sum of consecutive naturals, for example, 166201 + ... + 167518.

It is an arithmetic number, because the mean of its divisors is an integer number (55063800).

Almost surely, 2^219920821 is an apocalyptic number.

It is an amenable number.

219920821 is a deficient number, since it is larger than the sum of its proper divisors (334379).

219920821 is an equidigital number, since it uses as much as digits as its factorization.

219920821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334378.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 219920821 is about 14829.7276104452. The cubic root of 219920821 is about 603.6086424688.

The spelling of 219920821 in words is "two hundred nineteen million, nine hundred twenty thousand, eight hundred twenty-one".