261111645 has 12 divisors (see below), whose sum is σ = 452593596. Its totient is φ = 139259520.

The previous prime is 261111637. The next prime is 261111703. The reversal of 261111645 is 546111162.

261111645 is a `hidden beast` number, since 2 + 6 + 1 + 1 + 11 + 645 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 176066361 + 85045284 = 13269^2 + 9222^2 .

It is not a de Polignac number, because 261111645 - 2³ = 261111637 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2901196 + ... + 2901285.

It is an arithmetic number, because the mean of its divisors is an integer number (37716133).

Almost surely, 2^261111645 is an apocalyptic number.

It is an amenable number.

261111645 is a deficient number, since it is larger than the sum of its proper divisors (191481951).

261111645 is a wasteful number, since it uses less digits than its factorization.

261111645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5802492 (or 5802489 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 261111645 is about 16158.9493779763. The cubic root of 261111645 is about 639.1587620828.

The spelling of 261111645 in words is "two hundred sixty-one million, one hundred eleven thousand, six hundred forty-five".