21201220221210 has 96 divisors (see below), whose sum is σ = 55910337754752. Its totient is φ = 5572954558080.

The previous prime is 21201220221191. The next prime is 21201220221221. The reversal of 21201220221210 is 1212202210212.

It is a happy number.

21201220221210 is a `hidden beast` number, since 2 + 1 + 201 + 220 + 221 + 21 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 33083152 + ... + 33717908.

It is an arithmetic number, because the mean of its divisors is an integer number (582399351612).

Almost surely, 2^{21201220221210} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21201220221210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27955168877376).

21201220221210 is an abundant number, since it is smaller than the sum of its proper divisors (34709117533542).

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

21201220221210 is a wasteful number, since it uses less digits than its factorization.

21201220221210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 640068 (or 640065 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21201220221210 its reverse (1212202210212), we get a palindrome (22413422431422).

The spelling of 21201220221210 in words is "twenty-one trillion, two hundred one billion, two hundred twenty million, two hundred twenty-one thousand, two hundred ten".