1165621261 has 12 divisors (see below), whose sum is σ = 1359831900. Its totient is φ = 996226560.

The previous prime is 1165621243. The next prime is 1165621279. The reversal of 1165621261 is 1621265611.

It is an interprime number because it is at equal distance from previous prime (1165621243) and next prime (1165621279).

It can be written as a sum of positive squares in 2 ways, for example, as 910228900 + 255392361 = 30170^2 + 15981^2 .

It is not a de Polignac number, because 1165621261 - 2¹³ = 1165613069 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1165621211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16980 + ... + 51181.

It is an arithmetic number, because the mean of its divisors is an integer number (113319325).

Almost surely, 2^1165621261 is an apocalyptic number.

It is an amenable number.

1165621261 is a deficient number, since it is larger than the sum of its proper divisors (194210639).

1165621261 is an equidigital number, since it uses as much as digits as its factorization.

1165621261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68524 (or 68517 counting only the distinct ones).

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

The square root of 1165621261 is about 34141.1959515187. The cubic root of 1165621261 is about 1052.4120695438.

Adding to 1165621261 its reverse (1621265611), we get a palindrome (2786886872).

The spelling of 1165621261 in words is "one billion, one hundred sixty-five million, six hundred twenty-one thousand, two hundred sixty-one".