219145021 has 4 divisors (see below), whose sum is σ = 219250944. Its totient is φ = 219039100.

The previous prime is 219145009. The next prime is 219145027. The reversal of 219145021 is 120541912.

It is a happy number.

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 219145021 - 2²¹ = 217047869 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 (219145027) 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, 49795 + ... + 54016.

It is an arithmetic number, because the mean of its divisors is an integer number (54812736).

Almost surely, 2^219145021 is an apocalyptic number.

It is an amenable number.

219145021 is a deficient number, since it is larger than the sum of its proper divisors (105923).

219145021 is a wasteful number, since it uses less digits than its factorization.

219145021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105922.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 219145021 is about 14803.5475815765. The cubic root of 219145021 is about 602.8980362547.

Adding to 219145021 its reverse (120541912), we get a palindrome (339686933).

The spelling of 219145021 in words is "two hundred nineteen million, one hundred forty-five thousand, twenty-one".