21123000020 has 12 divisors (see below), whose sum is σ = 44358300084. Its totient is φ = 8449200000.

The previous prime is 21123000011. The next prime is 21123000047. The reversal of 21123000020 is 2000032112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 13438373776 + 7684626244 = 115924^2 + 87662^2 .

It is a super-4 number, since 4×21123000020⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21122999965 and 21123000010.

It is a congruent number.

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, 528074981 + ... + 528075020.

It is an arithmetic number, because the mean of its divisors is an integer number (3696525007).

Almost surely, 2^21123000020 is an apocalyptic number.

21123000020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21123000020 is an abundant number, since it is smaller than the sum of its proper divisors (23235300064).

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

21123000020 is a wasteful number, since it uses less digits than its factorization.

21123000020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056150010 (or 1056150008 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

Adding to 21123000020 its reverse (2000032112), we get a palindrome (23123032132).

The spelling of 21123000020 in words is "twenty-one billion, one hundred twenty-three million, twenty", and thus it is an aban number.