21531223057 has 2 divisors, whose sum is σ = 21531223058. Its totient is φ = 21531223056.

The previous prime is 21531223037. The next prime is 21531223069. The reversal of 21531223057 is 75032213512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21285642816 + 245580241 = 145896^2 + 15671^2 .

It is a cyclic number.

It is not a de Polignac number, because 21531223057 - 2⁷ = 21531222929 is a prime.

It is not a weakly prime, because it can be changed into another prime (21531223037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765611528 + 10765611529.

It is an arithmetic number, because the mean of its divisors is an integer number (10765611529).

Almost surely, 2^21531223057 is an apocalyptic number.

It is an amenable number.

21531223057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531223057 is an equidigital number, since it uses as much as digits as its factorization.

21531223057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12600, while the sum is 31.

Adding to 21531223057 its reverse (75032213512), we get a palindrome (96563436569).

The spelling of 21531223057 in words is "twenty-one billion, five hundred thirty-one million, two hundred twenty-three thousand, fifty-seven".