21585808331 has 2 divisors, whose sum is σ = 21585808332. Its totient is φ = 21585808330.

The previous prime is 21585808313. The next prime is 21585808403. The reversal of 21585808331 is 13380858512.

Together with previous prime (21585808313) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21585808331 - 2⁶ = 21585808267 is a prime.

It is a super-2 number, since 2×21585808331² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21585808031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10792904165 + 10792904166.

It is an arithmetic number, because the mean of its divisors is an integer number (10792904166).

Almost surely, 2^21585808331 is an apocalyptic number.

21585808331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21585808331 is an equidigital number, since it uses as much as digits as its factorization.

21585808331 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 230400, while the sum is 44.

The spelling of 21585808331 in words is "twenty-one billion, five hundred eighty-five million, eight hundred eight thousand, three hundred thirty-one".