21485857181 has 2 divisors, whose sum is σ = 21485857182. Its totient is φ = 21485857180.

The previous prime is 21485857163. The next prime is 21485857193. The reversal of 21485857181 is 18175858412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16314952900 + 5170904281 = 127730^2 + 71909^2 .

It is a cyclic number.

It is not a de Polignac number, because 21485857181 - 2¹⁸ = 21485595037 is a prime.

It is a super-2 number, since 2×21485857181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21485857111) 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, 10742928590 + 10742928591.

It is an arithmetic number, because the mean of its divisors is an integer number (10742928591).

Almost surely, 2^21485857181 is an apocalyptic number.

It is an amenable number.

21485857181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21485857181 is an equidigital number, since it uses as much as digits as its factorization.

21485857181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 716800, while the sum is 50.

The spelling of 21485857181 in words is "twenty-one billion, four hundred eighty-five million, eight hundred fifty-seven thousand, one hundred eighty-one".