21021023040 has 112 divisors (see below), whose sum is σ = 66821718528. Its totient is φ = 5598889984.

The previous prime is 21021023003. The next prime is 21021023047. The reversal of 21021023040 is 4032012012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021023047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 815794 + ... + 841166.

Almost surely, 2^21021023040 is an apocalyptic number.

21021023040 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 21021023040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33410859264).

21021023040 is an abundant number, since it is smaller than the sum of its proper divisors (45800695488).

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

21021023040 is a wasteful number, since it uses less digits than its factorization.

21021023040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26256 (or 26246 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

Adding to 21021023040 its reverse (4032012012), we get a palindrome (25053035052).

The spelling of 21021023040 in words is "twenty-one billion, twenty-one million, twenty-three thousand, forty".