21210111122100 has 72 divisors (see below), whose sum is σ = 61374382079808. Its totient is φ = 5655434188800.

The previous prime is 21210111122033. The next prime is 21210111122107. The reversal of 21210111122100 is 122111101212.

It is a happy number.

It is a super-2 number, since 2×21210111122100² (a number of 27 digits) contains 22 as substring.

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 21210111122100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210111122107) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 863469 + ... + 6570068.

Almost surely, 2^{21210111122100} is an apocalyptic number.

21210111122100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210111122100 is an abundant number, since it is smaller than the sum of its proper divisors (40164270957708).

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

21210111122100 is a wasteful number, since it uses less digits than its factorization.

21210111122100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7443065 (or 7443058 counting only the distinct ones).

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

Adding to 21210111122100 its reverse (122111101212), we get a palindrome (21332222223312).

The spelling of 21210111122100 in words is "twenty-one trillion, two hundred ten billion, one hundred eleven million, one hundred twenty-two thousand, one hundred".