263121721 has 2 divisors, whose sum is σ = 263121722. Its totient is φ = 263121720.

The previous prime is 263121701. The next prime is 263121737. The reversal of 263121721 is 127121362.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 253287225 + 9834496 = 15915^2 + 3136^2 .

It is a cyclic number.

It is not a de Polignac number, because 263121721 - 2¹⁷ = 262990649 is a prime.

It is not a weakly prime, because it can be changed into another prime (263121701) 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 as a sum of consecutive naturals, namely, 131560860 + 131560861.

It is an arithmetic number, because the mean of its divisors is an integer number (131560861).

Almost surely, 2^263121721 is an apocalyptic number.

It is an amenable number.

263121721 is a deficient number, since it is larger than the sum of its proper divisors (1).

263121721 is an equidigital number, since it uses as much as digits as its factorization.

263121721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 25.

The square root of 263121721 is about 16221.0271253087. The cubic root of 263121721 is about 640.7946842236.

The spelling of 263121721 in words is "two hundred sixty-three million, one hundred twenty-one thousand, seven hundred twenty-one".