21005123300 has 36 divisors (see below), whose sum is σ = 52092707520. Its totient is φ = 7201756320.

The previous prime is 21005123291. The next prime is 21005123303. The reversal of 21005123300 is 332150012.

It is a super-3 number, since 3×21005123300³ (a number of 32 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21005123303) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15002960 + ... + 15004359.

Almost surely, 2^21005123300 is an apocalyptic number.

21005123300 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21005123300 is an abundant number, since it is smaller than the sum of its proper divisors (31087584220).

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

21005123300 is a wasteful number, since it uses less digits than its factorization.

21005123300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30007340 (or 30007333 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 17.

Adding to 21005123300 its reverse (332150012), we get a palindrome (21337273312).

The spelling of 21005123300 in words is "twenty-one billion, five million, one hundred twenty-three thousand, three hundred".