561661655 has 8 divisors (see below), whose sum is σ = 675458784. Its totient is φ = 448352800.

The previous prime is 561661619. The next prime is 561661663. The reversal of 561661655 is 556166165.

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

It is not a de Polignac number, because 561661655 - 2¹² = 561657559 is a prime.

It is a Duffinian number.

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, 119531 + ... + 124140.

It is an arithmetic number, because the mean of its divisors is an integer number (84432348).

Almost surely, 2^561661655 is an apocalyptic number.

561661655 is a deficient number, since it is larger than the sum of its proper divisors (113797129).

561661655 is a wasteful number, since it uses less digits than its factorization.

561661655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244137.

The product of its digits is 162000, while the sum is 41.

The square root of 561661655 is about 23699.4019966749. The cubic root of 561661655 is about 825.0715114014.

The spelling of 561661655 in words is "five hundred sixty-one million, six hundred sixty-one thousand, six hundred fifty-five".