21210204440 has 32 divisors (see below), whose sum is σ = 49368582000. Its totient is φ = 8191526784.

The previous prime is 21210204437. The next prime is 21210204497. The reversal of 21210204440 is 4440201212.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 9141170 + ... + 9143489.

Almost surely, 2^21210204440 is an apocalyptic number.

21210204440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210204440 is an abundant number, since it is smaller than the sum of its proper divisors (28158377560).

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

21210204440 is a wasteful number, since it uses less digits than its factorization.

21210204440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18284699 (or 18284695 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21210204440 its reverse (4440201212), we get a palindrome (25650405652).

The spelling of 21210204440 in words is "twenty-one billion, two hundred ten million, two hundred four thousand, four hundred forty".