21155281171 has 2 divisors, whose sum is σ = 21155281172. Its totient is φ = 21155281170.

The previous prime is 21155281157. The next prime is 21155281177. The reversal of 21155281171 is 17118255112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21155281171 - 2²³ = 21146892563 is a prime.

It is not a weakly prime, because it can be changed into another prime (21155281177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577640585 + 10577640586.

It is an arithmetic number, because the mean of its divisors is an integer number (10577640586).

Almost surely, 2^21155281171 is an apocalyptic number.

21155281171 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155281171 is an equidigital number, since it uses as much as digits as its factorization.

21155281171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5600, while the sum is 34.

The spelling of 21155281171 in words is "twenty-one billion, one hundred fifty-five million, two hundred eighty-one thousand, one hundred seventy-one".