21105512206 has 24 divisors (see below), whose sum is σ = 33764279976. Its totient is φ = 9892368000.

The previous prime is 21105512201. The next prime is 21105512209. The reversal of 21105512206 is 60221550112.

It is a super-2 number, since 2×21105512206² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105512201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72340 + ... + 217816.

It is an arithmetic number, because the mean of its divisors is an integer number (1406844999).

Almost surely, 2^21105512206 is an apocalyptic number.

21105512206 is a deficient number, since it is larger than the sum of its proper divisors (12658767770).

21105512206 is a wasteful number, since it uses less digits than its factorization.

21105512206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145764 (or 145747 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 25.

The spelling of 21105512206 in words is "twenty-one billion, one hundred five million, five hundred twelve thousand, two hundred six".