21203241556 has 24 divisors (see below), whose sum is σ = 42434267456. Its totient is φ = 9081149760.

The previous prime is 21203241509. The next prime is 21203241557. The reversal of 21203241556 is 65514230212.

It is a super-2 number, since 2×21203241556² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203241557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 204441 + ... + 290176.

Almost surely, 2^21203241556 is an apocalyptic number.

It is an amenable number.

21203241556 is an abundant number, since it is smaller than the sum of its proper divisors (21231025900).

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

21203241556 is a wasteful number, since it uses less digits than its factorization.

21203241556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 496159 (or 496157 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 31.

Adding to 21203241556 its reverse (65514230212), we get a palindrome (86717471768).

The spelling of 21203241556 in words is "twenty-one billion, two hundred three million, two hundred forty-one thousand, five hundred fifty-six".