561219821 has 4 divisors (see below), whose sum is σ = 561547644. Its totient is φ = 560892000.

The previous prime is 561219817. The next prime is 561219823. The reversal of 561219821 is 128912165.

561219821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 415752100 + 145467721 = 20390^2 + 12061^2 .

It is a cyclic number.

It is not a de Polignac number, because 561219821 - 2² = 561219817 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 (561219823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 161330 + ... + 164771.

It is an arithmetic number, because the mean of its divisors is an integer number (140386911).

Almost surely, 2^561219821 is an apocalyptic number.

It is an amenable number.

561219821 is a deficient number, since it is larger than the sum of its proper divisors (327823).

561219821 is a wasteful number, since it uses less digits than its factorization.

561219821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 327822.

The product of its digits is 8640, while the sum is 35.

The square root of 561219821 is about 23690.0785351168. The cubic root of 561219821 is about 824.8551057445.

The spelling of 561219821 in words is "five hundred sixty-one million, two hundred nineteen thousand, eight hundred twenty-one".