21012121222200 has 288 divisors, whose sum is σ = 72379715616000. Its totient is φ = 5460611220480.

The previous prime is 21012121222199. The next prime is 21012121222249. The reversal of 21012121222200 is 222212121012.

It is a happy number.

21012121222200 is a `hidden beast` number, since 210 + 1 + 21 + 212 + 2 + 220 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 13475497 + ... + 14953703.

It is an arithmetic number, because the mean of its divisors is an integer number (251318457000).

Almost surely, 2^{21012121222200} is an apocalyptic number.

21012121222200 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 21012121222200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36189857808000).

21012121222200 is an abundant number, since it is smaller than the sum of its proper divisors (51367594393800).

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

21012121222200 is a wasteful number, since it uses less digits than its factorization.

21012121222200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1478431 (or 1478419 counting only the distinct ones).

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

Adding to 21012121222200 its reverse (222212121012), we get a palindrome (21234333343212).

The spelling of 21012121222200 in words is "twenty-one trillion, twelve billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred".