21521422057 has 2 divisors, whose sum is σ = 21521422058. Its totient is φ = 21521422056.

The previous prime is 21521421991. The next prime is 21521422063. The reversal of 21521422057 is 75022412512.

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., 18995454976 + 2525967081 = 137824^2 + 50259^2 .

It is a cyclic number.

It is not a de Polignac number, because 21521422057 - 2²³ = 21513033449 is a prime.

It is a super-2 number, since 2×21521422057² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21521423057) 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, 10760711028 + 10760711029.

It is an arithmetic number, because the mean of its divisors is an integer number (10760711029).

Almost surely, 2^21521422057 is an apocalyptic number.

It is an amenable number.

21521422057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21521422057 is an equidigital number, since it uses as much as digits as its factorization.

21521422057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11200, while the sum is 31.

Adding to 21521422057 its reverse (75022412512), we get a palindrome (96543834569).

The spelling of 21521422057 in words is "twenty-one billion, five hundred twenty-one million, four hundred twenty-two thousand, fifty-seven".