21211021211220 has 36 divisors (see below), whose sum is σ = 64340097674580. Its totient is φ = 5656272322944.

The previous prime is 21211021211209. The next prime is 21211021211243. The reversal of 21211021211220 is 2211212011212.

21211021211220 is a `hidden beast` number, since 2 + 1 + 211 + 0 + 21 + 211 + 220 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6211728767556 + 14999292443664 = 2492334^2 + 3872892^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a junction number, because it is equal to n+sod(n) for n = 21211021211193 and 21211021211202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58919503185 + ... + 58919503544.

It is an arithmetic number, because the mean of its divisors is an integer number (1787224935405).

Almost surely, 2^{21211021211220} is an apocalyptic number.

21211021211220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211021211220 is an abundant number, since it is smaller than the sum of its proper divisors (43129076463360).

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

21211021211220 is a wasteful number, since it uses less digits than its factorization.

21211021211220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117839006744 (or 117839006739 counting only the distinct ones).

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

Adding to 21211021211220 its reverse (2211212011212), we get a palindrome (23422233222432).

The spelling of 21211021211220 in words is "twenty-one trillion, two hundred eleven billion, twenty-one million, two hundred eleven thousand, two hundred twenty".