21212101210 has 24 divisors (see below), whose sum is σ = 39914046900. Its totient is φ = 8115932352.

The previous prime is 21212101193. The next prime is 21212101231. The reversal of 21212101210 is 1210121212.

21212101210 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in 2 ways, for example, as 20341320129 + 870781081 = 142623^2 + 29509^2 .

It is a super-3 number, since 3×21212101210³ (a number of 32 digits) contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 1999635 + ... + 2010214.

Almost surely, 2^21212101210 is an apocalyptic number.

21212101210 is a deficient number, since it is larger than the sum of its proper divisors (18701945690).

21212101210 is a wasteful number, since it uses less digits than its factorization.

21212101210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4009902 (or 4009879 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21212101210 its reverse (1210121212), we get a palindrome (22422222422).

The spelling of 21212101210 in words is "twenty-one billion, two hundred twelve million, one hundred one thousand, two hundred ten".