561981209 has 8 divisors (see below), whose sum is σ = 574283520. Its totient is φ = 549693376.

The previous prime is 561981181. The next prime is 561981239. The reversal of 561981209 is 902189165.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 561981209 - 2¹² = 561977113 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (561981239) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120332 + ... + 124914.

It is an arithmetic number, because the mean of its divisors is an integer number (71785440).

Almost surely, 2^561981209 is an apocalyptic number.

It is an amenable number.

561981209 is a deficient number, since it is larger than the sum of its proper divisors (12302311).

561981209 is a wasteful number, since it uses less digits than its factorization.

561981209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7239.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 561981209 is about 23706.1428536993. The cubic root of 561981209 is about 825.2279548840.

The spelling of 561981209 in words is "five hundred sixty-one million, nine hundred eighty-one thousand, two hundred nine".