21121202121210 has 128 divisors (see below), whose sum is σ = 57389632704000. Its totient is φ = 5525691664896.

The previous prime is 21121202121073. The next prime is 21121202121241. The reversal of 21121202121210 is 1212120212112.

21121202121210 is a `hidden beast` number, since 211 + 2 + 120 + 2 + 121 + 210 = 666.

It is a super-2 number, since 2×21121202121210² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 275987331 + ... + 276063849.

It is an arithmetic number, because the mean of its divisors is an integer number (448356505500).

Almost surely, 2^{21121202121210} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21121202121210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28694816352000).

21121202121210 is an abundant number, since it is smaller than the sum of its proper divisors (36268430582790).

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

21121202121210 is a wasteful number, since it uses less digits than its factorization.

21121202121210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95877 (or 95871 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21121202121210 its reverse (1212120212112), we get a palindrome (22333322333322).

The spelling of 21121202121210 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred two million, one hundred twenty-one thousand, two hundred ten".