21031200021 has 32 divisors (see below), whose sum is σ = 32171368320. Its totient is φ = 12106174464.

The previous prime is 21031200019. The next prime is 21031200061. The reversal of 21031200021 is 12000213012.

It is not a de Polignac number, because 21031200021 - 2¹ = 21031200019 is a prime.

It is a super-2 number, since 2×21031200021² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031200061) 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, 10765 + ... + 205373.

It is an arithmetic number, because the mean of its divisors is an integer number (1005355260).

Almost surely, 2^21031200021 is an apocalyptic number.

It is an amenable number.

21031200021 is a deficient number, since it is larger than the sum of its proper divisors (11140168299).

21031200021 is a wasteful number, since it uses less digits than its factorization.

21031200021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194805.

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21031200021 its reverse (12000213012), we get a palindrome (33031413033).

The spelling of 21031200021 in words is "twenty-one billion, thirty-one million, two hundred thousand, twenty-one".