1561515161 has 8 divisors (see below), whose sum is σ = 1655142984. Its totient is φ = 1468084480.

The previous prime is 1561515157. The next prime is 1561515223. The reversal of 1561515161 is 1615151651.

It can be written as a sum of positive squares in 4 ways, for example, as 814531600 + 746983561 = 28540^2 + 27331^2 .

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 1561515161 - 2² = 1561515157 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1561515961) 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, 32810 + ... + 64803.

It is an arithmetic number, because the mean of its divisors is an integer number (206892873).

Almost surely, 2^1561515161 is an apocalyptic number.

It is an amenable number.

1561515161 is a deficient number, since it is larger than the sum of its proper divisors (93627823).

1561515161 is an equidigital number, since it uses as much as digits as its factorization.

1561515161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98571.

The product of its digits is 4500, while the sum is 32.

The square root of 1561515161 is about 39516.0114510561. The cubic root of 1561515161 is about 1160.1533588859.

The spelling of 1561515161 in words is "one billion, five hundred sixty-one million, five hundred fifteen thousand, one hundred sixty-one".