263538661 has 2 divisors, whose sum is σ = 263538662. Its totient is φ = 263538660.

The previous prime is 263538659. The next prime is 263538673. The reversal of 263538661 is 166835362.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 182088036 + 81450625 = 13494^2 + 9025^2 .

It is a cyclic number.

It is not a de Polignac number, because 263538661 - 2¹ = 263538659 is a prime.

Together with 263538659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (263538061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 131769330 + 131769331.

It is an arithmetic number, because the mean of its divisors is an integer number (131769331).

Almost surely, 2^263538661 is an apocalyptic number.

It is an amenable number.

263538661 is a deficient number, since it is larger than the sum of its proper divisors (1).

263538661 is an equidigital number, since it uses as much as digits as its factorization.

263538661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 40.

The square root of 263538661 is about 16233.8738753262. The cubic root of 263538661 is about 641.1329711818.

The spelling of 263538661 in words is "two hundred sixty-three million, five hundred thirty-eight thousand, six hundred sixty-one".