263640557 has 2 divisors, whose sum is σ = 263640558. Its totient is φ = 263640556.

The previous prime is 263640529. The next prime is 263640563. The reversal of 263640557 is 755046362.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185123236 + 78517321 = 13606^2 + 8861^2 .

It is a cyclic number.

It is not a de Polignac number, because 263640557 - 2⁶ = 263640493 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 263640557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (263648557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 131820278 + 131820279.

It is an arithmetic number, because the mean of its divisors is an integer number (131820279).

Almost surely, 2^263640557 is an apocalyptic number.

It is an amenable number.

263640557 is a deficient number, since it is larger than the sum of its proper divisors (1).

263640557 is an equidigital number, since it uses as much as digits as its factorization.

263640557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 151200, while the sum is 38.

The square root of 263640557 is about 16237.0119480156. The cubic root of 263640557 is about 641.2155908970.

The spelling of 263640557 in words is "two hundred sixty-three million, six hundred forty thousand, five hundred fifty-seven".