262661561 has 4 divisors (see below), whose sum is σ = 262823652. Its totient is φ = 262499472.

The previous prime is 262661549. The next prime is 262661563. The reversal of 262661561 is 165166262.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6661561 + 256000000 = 2581^2 + 16000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-262661561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (262661563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78590 + ... + 81863.

It is an arithmetic number, because the mean of its divisors is an integer number (65705913).

Almost surely, 2^262661561 is an apocalyptic number.

It is an amenable number.

262661561 is a deficient number, since it is larger than the sum of its proper divisors (162091).

262661561 is a wasteful number, since it uses less digits than its factorization.

262661561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162090.

The product of its digits is 25920, while the sum is 35.

The square root of 262661561 is about 16206.8368597947. The cubic root of 262661561 is about 640.4209153317.

The spelling of 262661561 in words is "two hundred sixty-two million, six hundred sixty-one thousand, five hundred sixty-one".