219721097 has 4 divisors (see below), whose sum is σ = 220664340. Its totient is φ = 218777856.

The previous prime is 219721079. The next prime is 219721121. The reversal of 219721097 is 790127912.

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 40589641 + 179131456 = 6371^2 + 13384^2 .

It is a cyclic number.

It is not a de Polignac number, because 219721097 - 2¹⁰ = 219720073 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 219721097.

It is not an unprimeable number, because it can be changed into a prime (219721067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 471272 + ... + 471737.

It is an arithmetic number, because the mean of its divisors is an integer number (55166085).

Almost surely, 2^219721097 is an apocalyptic number.

It is an amenable number.

219721097 is a deficient number, since it is larger than the sum of its proper divisors (943243).

219721097 is an equidigital number, since it uses as much as digits as its factorization.

219721097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 943242.

The product of its (nonzero) digits is 15876, while the sum is 38.

The square root of 219721097 is about 14822.9921743216. The cubic root of 219721097 is about 603.4258620709.

The spelling of 219721097 in words is "two hundred nineteen million, seven hundred twenty-one thousand, ninety-seven".