21531100203 has 6 divisors (see below), whose sum is σ = 31100478084. Its totient is φ = 14354066796.

The previous prime is 21531100177. The next prime is 21531100211. The reversal of 21531100203 is 30200113512.

It is not a de Polignac number, because 21531100203 - 2²⁸ = 21262664747 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21531100603) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1196172225 + ... + 1196172242.

It is an arithmetic number, because the mean of its divisors is an integer number (5183413014).

Almost surely, 2^21531100203 is an apocalyptic number.

21531100203 is a deficient number, since it is larger than the sum of its proper divisors (9569377881).

21531100203 is a wasteful number, since it uses less digits than its factorization.

21531100203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2392344473 (or 2392344470 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

Adding to 21531100203 its reverse (30200113512), we get a palindrome (51731213715).

The spelling of 21531100203 in words is "twenty-one billion, five hundred thirty-one million, one hundred thousand, two hundred three".