21203241555 has 32 divisors (see below), whose sum is σ = 34420930560. Its totient is φ = 11143314560.

The previous prime is 21203241509. The next prime is 21203241557. The reversal of 21203241555 is 55514230212.

It is not a de Polignac number, because 21203241555 - 2⁸ = 21203241299 is a prime.

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 31 ways as a sum of consecutive naturals, for example, 2704381 + ... + 2712209.

It is an arithmetic number, because the mean of its divisors is an integer number (1075654080).

Almost surely, 2^21203241555 is an apocalyptic number.

21203241555 is a deficient number, since it is larger than the sum of its proper divisors (13217689005).

21203241555 is a wasteful number, since it uses less digits than its factorization.

21203241555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10451.

The product of its (nonzero) digits is 12000, while the sum is 30.

Adding to 21203241555 its reverse (55514230212), we get a palindrome (76717471767).

The spelling of 21203241555 in words is "twenty-one billion, two hundred three million, two hundred forty-one thousand, five hundred fifty-five".