1261612165 has 16 divisors (see below), whose sum is σ = 1655712576. Its totient is φ = 915232000.

The previous prime is 1261612151. The next prime is 1261612193. The reversal of 1261612165 is 5612161621.

It is not a de Polignac number, because 1261612165 - 2¹¹ = 1261610117 is a prime.

It is a super-3 number, since 3×1261612165³ (a number of 28 digits) contains 333 as substring.

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 15 ways as a sum of consecutive naturals, for example, 6547 + ... + 50656.

It is an arithmetic number, because the mean of its divisors is an integer number (103482036).

Almost surely, 2^1261612165 is an apocalyptic number.

It is an amenable number.

1261612165 is a deficient number, since it is larger than the sum of its proper divisors (394100411).

1261612165 is a wasteful number, since it uses less digits than its factorization.

1261612165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57620.

The product of its digits is 4320, while the sum is 31.

The square root of 1261612165 is about 35519.1802411035. The cubic root of 1261612165 is about 1080.5427555982.

Adding to 1261612165 its reverse (5612161621), we get a palindrome (6873773786).

The spelling of 1261612165 in words is "one billion, two hundred sixty-one million, six hundred twelve thousand, one hundred sixty-five".