21021211021220 has 24 divisors (see below), whose sum is σ = 44146065487608. Its totient is φ = 8408194438400.

The previous prime is 21021211021159. The next prime is 21021211021301. The reversal of 21021211021220 is 2212011212012.

It can be written as a sum of positive squares in 4 ways, for example, as 14044565721664 + 6976645299556 = 3747608^2 + 2641334^2 .

It is a super-2 number, since 2×21021211021220² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17528201 + ... + 18689040.

It is an arithmetic number, because the mean of its divisors is an integer number (1839419395317).

Almost surely, 2^{21021211021220} is an apocalyptic number.

21021211021220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021211021220 is an abundant number, since it is smaller than the sum of its proper divisors (23124854466388).

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

21021211021220 is a wasteful number, since it uses less digits than its factorization.

21021211021220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36246271 (or 36246269 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21021211021220 its reverse (2212011212012), we get a palindrome (23233222233232).

The spelling of 21021211021220 in words is "twenty-one trillion, twenty-one billion, two hundred eleven million, twenty-one thousand, two hundred twenty".