21203241540 has 144 divisors (see below), whose sum is σ = 66218687808. Its totient is φ = 5039129088.

The previous prime is 21203241509. The next prime is 21203241557. The reversal of 21203241540 is 4514230212.

It is a self number, because there is not a number n which added to its sum of digits gives 21203241540.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 639819 + ... + 672141.

Almost surely, 2^21203241540 is an apocalyptic number.

21203241540 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 21203241540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33109343904).

21203241540 is an abundant number, since it is smaller than the sum of its proper divisors (45015446268).

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

21203241540 is a wasteful number, since it uses less digits than its factorization.

21203241540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32406 (or 32375 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

Adding to 21203241540 its reverse (4514230212), we get a palindrome (25717471752).

The spelling of 21203241540 in words is "twenty-one billion, two hundred three million, two hundred forty-one thousand, five hundred forty".