21471120257 has 2 divisors, whose sum is σ = 21471120258. Its totient is φ = 21471120256.

The previous prime is 21471120191. The next prime is 21471120277. The reversal of 21471120257 is 75202117412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17981737216 + 3489383041 = 134096^2 + 59071^2 .

It is a cyclic number.

It is not a de Polignac number, because 21471120257 - 2⁸ = 21471120001 is a prime.

It is a super-2 number, since 2×21471120257² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21471120277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10735560128 + 10735560129.

It is an arithmetic number, because the mean of its divisors is an integer number (10735560129).

Almost surely, 2^21471120257 is an apocalyptic number.

It is an amenable number.

21471120257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21471120257 is an equidigital number, since it uses as much as digits as its factorization.

21471120257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7840, while the sum is 32.

Adding to 21471120257 its reverse (75202117412), we get a palindrome (96673237669).

The spelling of 21471120257 in words is "twenty-one billion, four hundred seventy-one million, one hundred twenty thousand, two hundred fifty-seven".