21000202120 has 16 divisors (see below), whose sum is σ = 47250454860. Its totient is φ = 8400080832.

The previous prime is 21000202087. The next prime is 21000202133. The reversal of 21000202120 is 2120200012.

It can be written as a sum of positive squares in 2 ways, for example, as 20957194756 + 43007364 = 144766^2 + 6558^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21000202097 and 21000202106.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 262502487 + ... + 262502566.

Almost surely, 2^21000202120 is an apocalyptic number.

21000202120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000202120 is an abundant number, since it is smaller than the sum of its proper divisors (26250252740).

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

21000202120 is a wasteful number, since it uses less digits than its factorization.

21000202120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525005064 (or 525005060 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21000202120 its reverse (2120200012), we get a palindrome (23120402132).

The spelling of 21000202120 in words is "twenty-one billion, two hundred two thousand, one hundred twenty".