21121311210 has 32 divisors (see below), whose sum is σ = 50735194560. Its totient is φ = 5627455488.

The previous prime is 21121311191. The next prime is 21121311307. The reversal of 21121311210 is 1211312112.

It is a super-2 number, since 2×21121311210² (a number of 21 digits) contains 22 as substring.

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 21121311210.

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, 270720 + ... + 339899.

It is an arithmetic number, because the mean of its divisors is an integer number (1585474830).

Almost surely, 2^21121311210 is an apocalyptic number.

21121311210 is an abundant number, since it is smaller than the sum of its proper divisors (29613883350).

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

21121311210 is a wasteful number, since it uses less digits than its factorization.

21121311210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 611782.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21121311210 its reverse (1211312112), we get a palindrome (22332623322).

The spelling of 21121311210 in words is "twenty-one billion, one hundred twenty-one million, three hundred eleven thousand, two hundred ten".