263671561 has 4 divisors (see below), whose sum is σ = 263704324. Its totient is φ = 263638800.

The previous prime is 263671559. The next prime is 263671613. The reversal of 263671561 is 165176362.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 152769600 + 110901961 = 12360^2 + 10531^2 .

It is a cyclic number.

It is not a de Polignac number, because 263671561 - 2¹ = 263671559 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 263671561.

It is not an unprimeable number, because it can be changed into a prime (263671501) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 4951 + ... + 23491.

It is an arithmetic number, because the mean of its divisors is an integer number (65926081).

Almost surely, 2^263671561 is an apocalyptic number.

It is an amenable number.

263671561 is a deficient number, since it is larger than the sum of its proper divisors (32763).

263671561 is a wasteful number, since it uses less digits than its factorization.

263671561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32762.

The product of its digits is 45360, while the sum is 37.

The square root of 263671561 is about 16237.9666522628. The cubic root of 263671561 is about 641.2407254579.

The spelling of 263671561 in words is "two hundred sixty-three million, six hundred seventy-one thousand, five hundred sixty-one".