21221121210 has 16 divisors (see below), whose sum is σ = 50930690976. Its totient is φ = 5658965648.

The previous prime is 21221121167. The next prime is 21221121241. The reversal of 21221121210 is 1212112212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21221121210.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 353685324 + ... + 353685383.

It is an arithmetic number, because the mean of its divisors is an integer number (3183168186).

Almost surely, 2^21221121210 is an apocalyptic number.

21221121210 is an abundant number, since it is smaller than the sum of its proper divisors (29709569766).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21221121210 is a wasteful number, since it uses less digits than its factorization.

21221121210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 707370717.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21221121210 its reverse (1212112212), we get a palindrome (22433233422).

The spelling of 21221121210 in words is "twenty-one billion, two hundred twenty-one million, one hundred twenty-one thousand, two hundred ten".