21012121121100 has 36 divisors (see below), whose sum is σ = 60795070444584. Its totient is φ = 5603232298880.

The previous prime is 21012121121077. The next prime is 21012121121111. The reversal of 21012121121100 is 112112121012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21012121121100.

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, 35020201569 + ... + 35020202168.

It is an arithmetic number, because the mean of its divisors is an integer number (1688751956794).

Almost surely, 2^{21012121121100} is an apocalyptic number.

21012121121100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012121121100 is an abundant number, since it is smaller than the sum of its proper divisors (39782949323484).

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

21012121121100 is a wasteful number, since it uses less digits than its factorization.

21012121121100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70040403754 (or 70040403747 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21012121121100 its reverse (112112121012), we get a palindrome (21124233242112).

The spelling of 21012121121100 in words is "twenty-one trillion, twelve billion, one hundred twenty-one million, one hundred twenty-one thousand, one hundred".