21864581205 has 16 divisors (see below), whose sum is σ = 35197955520. Its totient is φ = 11589568128.

The previous prime is 21864581191. The next prime is 21864581213. The reversal of 21864581205 is 50218546812.

It is not a de Polignac number, because 21864581205 - 2⁵ = 21864581173 is a prime.

It is a super-2 number, since 2×21864581205² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4468840 + ... + 4473729.

It is an arithmetic number, because the mean of its divisors is an integer number (2199872220).

Almost surely, 2^21864581205 is an apocalyptic number.

It is an amenable number.

21864581205 is a deficient number, since it is larger than the sum of its proper divisors (13333374315).

21864581205 is a wasteful number, since it uses less digits than its factorization.

21864581205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8942740.

The product of its (nonzero) digits is 153600, while the sum is 42.

The spelling of 21864581205 in words is "twenty-one billion, eight hundred sixty-four million, five hundred eighty-one thousand, two hundred five".