21545203111 has 4 divisors (see below), whose sum is σ = 21898403224. Its totient is φ = 21192003000.

The previous prime is 21545203093. The next prime is 21545203117. The reversal of 21545203111 is 11130254512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21545203111 - 2⁷ = 21545202983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545203117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 176599965 + ... + 176600086.

It is an arithmetic number, because the mean of its divisors is an integer number (5474600806).

Almost surely, 2^21545203111 is an apocalyptic number.

21545203111 is a deficient number, since it is larger than the sum of its proper divisors (353200113).

21545203111 is an equidigital number, since it uses as much as digits as its factorization.

21545203111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353200112.

The product of its (nonzero) digits is 1200, while the sum is 25.

Adding to 21545203111 its reverse (11130254512), we get a palindrome (32675457623).

The spelling of 21545203111 in words is "twenty-one billion, five hundred forty-five million, two hundred three thousand, one hundred eleven".