21021111221057 has 2 divisors, whose sum is σ = 21021111221058. Its totient is φ = 21021111221056.

The previous prime is 21021111220987. The next prime is 21021111221093. The reversal of 21021111221057 is 75012211112012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15754159660801 + 5266951560256 = 3969151^2 + 2294984^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021111221057 - 2⁴⁰ = 19921599593281 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021111221657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510555610528 + 10510555610529.

It is an arithmetic number, because the mean of its divisors is an integer number (10510555610529).

Almost surely, 2^{21021111221057} is an apocalyptic number.

It is an amenable number.

21021111221057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021111221057 is an equidigital number, since it uses as much as digits as its factorization.

21021111221057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 560, while the sum is 26.

Adding to 21021111221057 its reverse (75012211112012), we get a palindrome (96033322333069).

The spelling of 21021111221057 in words is "twenty-one trillion, twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, fifty-seven".