1261224165 has 16 divisors (see below), whose sum is σ = 2067178176. Its totient is φ = 656246400.

The previous prime is 1261224157. The next prime is 1261224187. The reversal of 1261224165 is 5614221621.

It is not a de Polignac number, because 1261224165 - 2³ = 1261224157 is a prime.

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, 1024771 + ... + 1026000.

It is an arithmetic number, because the mean of its divisors is an integer number (129198636).

Almost surely, 2^1261224165 is an apocalyptic number.

1261224165 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261224165 is a deficient number, since it is larger than the sum of its proper divisors (805954011).

1261224165 is a wasteful number, since it uses less digits than its factorization.

1261224165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2050820.

The product of its digits is 5760, while the sum is 30.

The square root of 1261224165 is about 35513.7179833371. The cubic root of 1261224165 is about 1080.4319731175.

Adding to 1261224165 its reverse (5614221621), we get a palindrome (6875445786).

The spelling of 1261224165 in words is "one billion, two hundred sixty-one million, two hundred twenty-four thousand, one hundred sixty-five".