561209820 has 24 divisors (see below), whose sum is σ = 1571387664. Its totient is φ = 149655936.

The previous prime is 561209819. The next prime is 561209837. The reversal of 561209820 is 28902165.

561209820 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4676689 + ... + 4676808.

It is an arithmetic number, because the mean of its divisors is an integer number (65474486).

Almost surely, 2^561209820 is an apocalyptic number.

It is an amenable number.

561209820 is an abundant number, since it is smaller than the sum of its proper divisors (1010177844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

561209820 is a wasteful number, since it uses less digits than its factorization.

561209820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9353509 (or 9353507 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 561209820 is about 23689.8674542514. The cubic root of 561209820 is about 824.8502060453.

The spelling of 561209820 in words is "five hundred sixty-one million, two hundred nine thousand, eight hundred twenty".