21012004020 has 96 divisors (see below), whose sum is σ = 67610140416. Its totient is φ = 4776192000.

The previous prime is 21012004019. The next prime is 21012004081. The reversal of 21012004020 is 2040021012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21012003987 and 21012004005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 62181 + ... + 214220.

It is an arithmetic number, because the mean of its divisors is an integer number (704272296).

Almost surely, 2^21012004020 is an apocalyptic number.

21012004020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012004020 is an abundant number, since it is smaller than the sum of its proper divisors (46598136396).

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

21012004020 is a wasteful number, since it uses less digits than its factorization.

21012004020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 276601 (or 276599 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21012004020 its reverse (2040021012), we get a palindrome (23052025032).

The spelling of 21012004020 in words is "twenty-one billion, twelve million, four thousand, twenty".