21001054240 has 96 divisors (see below), whose sum is σ = 49981394736. Its totient is φ = 8338636800.

The previous prime is 21001054231. The next prime is 21001054241. The reversal of 21001054240 is 4245010012.

It can be written as a sum of positive squares in 8 ways, for example, as 32855824 + 20968198416 = 5732^2 + 144804^2 .

It is not an unprimeable number, because it can be changed into a prime (21001054241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16141590 + ... + 16142890.

Almost surely, 2^21001054240 is an apocalyptic number.

21001054240 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 21001054240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24990697368).

21001054240 is an abundant number, since it is smaller than the sum of its proper divisors (28980340496).

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

21001054240 is a wasteful number, since it uses less digits than its factorization.

21001054240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1982 (or 1974 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 21001054240 its reverse (4245010012), we get a palindrome (25246064252).

The spelling of 21001054240 in words is "twenty-one billion, one million, fifty-four thousand, two hundred forty".