21020040000 has 280 divisors, whose sum is σ = 77223030720. Its totient is φ = 5605056000.

The previous prime is 21020039981. The next prime is 21020040007. The reversal of 21020040000 is 4002012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020040007) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1070269 + ... + 1089731.

Almost surely, 2^21020040000 is an apocalyptic number.

21020040000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020040000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38611515360).

21020040000 is an abundant number, since it is smaller than the sum of its proper divisors (56202990720).

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

21020040000 is an equidigital number, since it uses as much as digits as its factorization.

21020040000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19504 (or 19473 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

Adding to 21020040000 its reverse (4002012), we get a palindrome (21024042012).

The spelling of 21020040000 in words is "twenty-one billion, twenty million, forty thousand".