21203434545 has 32 divisors (see below), whose sum is σ = 34100352000. Its totient is φ = 11250299904.

The previous prime is 21203434531. The next prime is 21203434619. The reversal of 21203434545 is 54543430212.

It is not a de Polignac number, because 21203434545 - 2⁵ = 21203434513 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6145981 + ... + 6149429.

It is an arithmetic number, because the mean of its divisors is an integer number (1065636000).

Almost surely, 2^21203434545 is an apocalyptic number.

It is an amenable number.

21203434545 is a deficient number, since it is larger than the sum of its proper divisors (12896917455).

21203434545 is a wasteful number, since it uses less digits than its factorization.

21203434545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5449.

The product of its (nonzero) digits is 57600, while the sum is 33.

Adding to 21203434545 its reverse (54543430212), we get a palindrome (75746864757).

The spelling of 21203434545 in words is "twenty-one billion, two hundred three million, four hundred thirty-four thousand, five hundred forty-five".