261668145 has 32 divisors (see below), whose sum is σ = 425779200. Its totient is φ = 137202624.

The previous prime is 261668137. The next prime is 261668149. The reversal of 261668145 is 541866162.

It is a happy number.

It is not a de Polignac number, because 261668145 - 2³ = 261668137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261668149) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 519964 + ... + 520466.

It is an arithmetic number, because the mean of its divisors is an integer number (13305600).

Almost surely, 2^261668145 is an apocalyptic number.

It is an amenable number.

261668145 is a deficient number, since it is larger than the sum of its proper divisors (164111055).

261668145 is a wasteful number, since it uses less digits than its factorization.

261668145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1029.

The product of its digits is 69120, while the sum is 39.

The square root of 261668145 is about 16176.1597729498. The cubic root of 261668145 is about 639.6125136544.

The spelling of 261668145 in words is "two hundred sixty-one million, six hundred sixty-eight thousand, one hundred forty-five".