1565555161 has 4 divisors (see below), whose sum is σ = 1566038800. Its totient is φ = 1565071524.

The previous prime is 1565555129. The next prime is 1565555197. The reversal of 1565555161 is 1615555651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1565555161 - 2⁵ = 1565555129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1565555861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 236931 + ... + 243448.

It is an arithmetic number, because the mean of its divisors is an integer number (391509700).

Almost surely, 2^1565555161 is an apocalyptic number.

It is an amenable number.

1565555161 is a deficient number, since it is larger than the sum of its proper divisors (483639).

1565555161 is an equidigital number, since it uses as much as digits as its factorization.

1565555161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 483638.

The product of its digits is 112500, while the sum is 40.

The square root of 1565555161 is about 39567.0969493593. The cubic root of 1565555161 is about 1161.1530253963.

The spelling of 1565555161 in words is "one billion, five hundred sixty-five million, five hundred fifty-five thousand, one hundred sixty-one".