21212320221000 has 384 divisors, whose sum is σ = 73322434504800. Its totient is φ = 5529225062400.

The previous prime is 21212320220921. The next prime is 21212320221013. The reversal of 21212320221000 is 12202321212.

21212320221000 is a `hidden beast` number, since 2 + 121 + 2 + 320 + 221 + 0 + 0 + 0 = 666.

It can be written as a sum of positive squares in 16 ways, for example, as 9833153837796 + 11379166383204 = 3135786^2 + 3373302^2 .

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 95 ways as a sum of consecutive naturals, for example, 128230342 + ... + 128395658.

Almost surely, 2^{21212320221000} is an apocalyptic number.

21212320221000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212320221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36661217252400).

21212320221000 is an abundant number, since it is smaller than the sum of its proper divisors (52110114283800).

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

21212320221000 is a wasteful number, since it uses less digits than its factorization.

21212320221000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165666 (or 165649 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21212320221000 its reverse (12202321212), we get a palindrome (21224522542212).

The spelling of 21212320221000 in words is "twenty-one trillion, two hundred twelve billion, three hundred twenty million, two hundred twenty-one thousand".