21864452081 has 4 divisors (see below), whose sum is σ = 21865155312. Its totient is φ = 21863748852.

The previous prime is 21864452033. The next prime is 21864452107. The reversal of 21864452081 is 18025446812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21864452081 - 2⁶ = 21864452017 is a prime.

It is a super-2 number, since 2×21864452081² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21864452381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 302711 + ... + 367916.

It is an arithmetic number, because the mean of its divisors is an integer number (5466288828).

Almost surely, 2^21864452081 is an apocalyptic number.

It is an amenable number.

21864452081 is a deficient number, since it is larger than the sum of its proper divisors (703231).

21864452081 is an equidigital number, since it uses as much as digits as its factorization.

21864452081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 703230.

The product of its (nonzero) digits is 122880, while the sum is 41.

Adding to 21864452081 its reverse (18025446812), we get a palindrome (39889898893).

The spelling of 21864452081 in words is "twenty-one billion, eight hundred sixty-four million, four hundred fifty-two thousand, eighty-one".