21200123021 has 32 divisors (see below), whose sum is σ = 27019699200. Its totient is φ = 16154772480.

The previous prime is 21200122961. The next prime is 21200123033. The reversal of 21200123021 is 12032100212.

It is a happy number.

It is not a de Polignac number, because 21200123021 - 2¹⁰ = 21200121997 is a prime.

It is a super-2 number, since 2×21200123021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21200122987 and 21200123005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200123041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 864710 + ... + 888888.

It is an arithmetic number, because the mean of its divisors is an integer number (844365600).

Almost surely, 2^21200123021 is an apocalyptic number.

It is an amenable number.

21200123021 is a deficient number, since it is larger than the sum of its proper divisors (5819576179).

21200123021 is a wasteful number, since it uses less digits than its factorization.

21200123021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24449.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21200123021 its reverse (12032100212), we get a palindrome (33232223233).

The spelling of 21200123021 in words is "twenty-one billion, two hundred million, one hundred twenty-three thousand, twenty-one".