21208271057 has 2 divisors, whose sum is σ = 21208271058. Its totient is φ = 21208271056.

The previous prime is 21208271027. The next prime is 21208271059. The reversal of 21208271057 is 75017280212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21171414016 + 36857041 = 145504^2 + 6071^2 .

It is a cyclic number.

It is not a de Polignac number, because 21208271057 - 2¹⁴ = 21208254673 is a prime.

It is a super-2 number, since 2×21208271057² (a number of 21 digits) contains 22 as substring.

Together with 21208271059, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21208271059) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10604135528 + 10604135529.

It is an arithmetic number, because the mean of its divisors is an integer number (10604135529).

Almost surely, 2^21208271057 is an apocalyptic number.

It is an amenable number.

21208271057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21208271057 is an equidigital number, since it uses as much as digits as its factorization.

21208271057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15680, while the sum is 35.

The spelling of 21208271057 in words is "twenty-one billion, two hundred eight million, two hundred seventy-one thousand, fifty-seven".