21012021000 has 128 divisors (see below), whose sum is σ = 72841766400. Its totient is φ = 5603198400.

The previous prime is 21012020933. The next prime is 21012021001. The reversal of 21012021000 is 12021012.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21012021001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 362112 + ... + 416111.

It is an arithmetic number, because the mean of its divisors is an integer number (569076300).

Almost surely, 2^21012021000 is an apocalyptic number.

21012021000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012021000 is an abundant number, since it is smaller than the sum of its proper divisors (51829745400).

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

21012021000 is a wasteful number, since it uses less digits than its factorization.

21012021000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778253 (or 778233 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21012021000 its reverse (12021012), we get a palindrome (21024042012).

The spelling of 21012021000 in words is "twenty-one billion, twelve million, twenty-one thousand".