21825727081 has 2 divisors, whose sum is σ = 21825727082. Its totient is φ = 21825727080.

The previous prime is 21825727073. The next prime is 21825727109. The reversal of 21825727081 is 18072752812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13620990681 + 8204736400 = 116709^2 + 90580^2 .

It is a cyclic number.

It is not a de Polignac number, because 21825727081 - 2³ = 21825727073 is a prime.

It is a super-2 number, since 2×21825727081² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21825727181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10912863540 + 10912863541.

It is an arithmetic number, because the mean of its divisors is an integer number (10912863541).

Almost surely, 2^21825727081 is an apocalyptic number.

It is an amenable number.

21825727081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21825727081 is an equidigital number, since it uses as much as digits as its factorization.

21825727081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 125440, while the sum is 43.

The spelling of 21825727081 in words is "twenty-one billion, eight hundred twenty-five million, seven hundred twenty-seven thousand, eighty-one".