21324203351557 has 2 divisors, whose sum is σ = 21324203351558. Its totient is φ = 21324203351556.

The previous prime is 21324203351509. The next prime is 21324203351569. The reversal of 21324203351557 is 75515330242312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11839441840801 + 9484761510756 = 3440849^2 + 3079734^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21324203351557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21324203351587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10662101675778 + 10662101675779.

It is an arithmetic number, because the mean of its divisors is an integer number (10662101675779).

Almost surely, 2^{21324203351557} is an apocalyptic number.

It is an amenable number.

21324203351557 is a deficient number, since it is larger than the sum of its proper divisors (1).

21324203351557 is an equidigital number, since it uses as much as digits as its factorization.

21324203351557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 756000, while the sum is 43.

Adding to 21324203351557 its reverse (75515330242312), we get a palindrome (96839533593869).

The spelling of 21324203351557 in words is "twenty-one trillion, three hundred twenty-four billion, two hundred three million, three hundred fifty-one thousand, five hundred fifty-seven".