21404330257 has 2 divisors, whose sum is σ = 21404330258. Its totient is φ = 21404330256.

The previous prime is 21404330111. The next prime is 21404330263. The reversal of 21404330257 is 75203340412.

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., 21110927616 + 293402641 = 145296^2 + 17129^2 .

It is a cyclic number.

It is not a de Polignac number, because 21404330257 - 2²⁷ = 21270112529 is a prime.

It is not a weakly prime, because it can be changed into another prime (21404330287) 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 as a sum of consecutive naturals, namely, 10702165128 + 10702165129.

It is an arithmetic number, because the mean of its divisors is an integer number (10702165129).

Almost surely, 2^21404330257 is an apocalyptic number.

It is an amenable number.

21404330257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21404330257 is an equidigital number, since it uses as much as digits as its factorization.

21404330257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 31.

Adding to 21404330257 its reverse (75203340412), we get a palindrome (96607670669).

The spelling of 21404330257 in words is "twenty-one billion, four hundred four million, three hundred thirty thousand, two hundred fifty-seven".