261615161 has 4 divisors (see below), whose sum is σ = 275384400. Its totient is φ = 247845924.

The previous prime is 261615083. The next prime is 261615173. The reversal of 261615161 is 161516162.

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 261615161 - 2¹⁰ = 261614137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261615181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6884591 + ... + 6884628.

It is an arithmetic number, because the mean of its divisors is an integer number (68846100).

Almost surely, 2^261615161 is an apocalyptic number.

It is an amenable number.

261615161 is a deficient number, since it is larger than the sum of its proper divisors (13769239).

261615161 is a wasteful number, since it uses less digits than its factorization.

261615161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13769238.

The product of its digits is 2160, while the sum is 29.

The square root of 261615161 is about 16174.5219712979. The cubic root of 261615161 is about 639.5693399912.

The spelling of 261615161 in words is "two hundred sixty-one million, six hundred fifteen thousand, one hundred sixty-one".