1561006565 has 4 divisors (see below), whose sum is σ = 1873207884. Its totient is φ = 1248805248.

The previous prime is 1561006561. The next prime is 1561006609. The reversal of 1561006565 is 5656001651.

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 853925284 + 707081281 = 29222^2 + 26591^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561006565 - 2² = 1561006561 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 (1561006561) 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, 156100652 + ... + 156100661.

It is an arithmetic number, because the mean of its divisors is an integer number (468301971).

Almost surely, 2^1561006565 is an apocalyptic number.

It is an amenable number.

1561006565 is a deficient number, since it is larger than the sum of its proper divisors (312201319).

1561006565 is an equidigital number, since it uses as much as digits as its factorization.

1561006565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312201318.

The product of its (nonzero) digits is 27000, while the sum is 35.

The square root of 1561006565 is about 39509.5756114894. The cubic root of 1561006565 is about 1160.0273886221.

The spelling of 1561006565 in words is "one billion, five hundred sixty-one million, six thousand, five hundred sixty-five".