21012121200 has 180 divisors, whose sum is σ = 78298243800. Its totient is φ = 4802757120.

The previous prime is 21012121189. The next prime is 21012121213. The reversal of 21012121200 is 212121012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 119875 + ... + 237474.

Almost surely, 2^21012121200 is an apocalyptic number.

21012121200 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012121200 is an abundant number, since it is smaller than the sum of its proper divisors (57286122600).

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

21012121200 is a wasteful number, since it uses less digits than its factorization.

21012121200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357384 (or 357366 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21012121200 its reverse (212121012), we get a palindrome (21224242212).

The spelling of 21012121200 in words is "twenty-one billion, twelve million, one hundred twenty-one thousand, two hundred".