21200001021 has 16 divisors (see below), whose sum is σ = 31636665600. Its totient is φ = 14030168544.

The previous prime is 21200001019. The next prime is 21200001041. The reversal of 21200001021 is 12010000212.

It is not a de Polignac number, because 21200001021 - 2¹ = 21200001019 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21200000994 and 21200001012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200001001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2861941 + ... + 2869338.

It is an arithmetic number, because the mean of its divisors is an integer number (1977291600).

Almost surely, 2^21200001021 is an apocalyptic number.

It is an amenable number.

21200001021 is a deficient number, since it is larger than the sum of its proper divisors (10436664579).

21200001021 is a wasteful number, since it uses less digits than its factorization.

21200001021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5731425 (or 5731419 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21200001021 its reverse (12010000212), we get a palindrome (33210001233).

The spelling of 21200001021 in words is "twenty-one billion, two hundred million, one thousand, twenty-one".