21553251011 has 4 divisors (see below), whose sum is σ = 21554380224. Its totient is φ = 21552121800.

The previous prime is 21553250977. The next prime is 21553251017. The reversal of 21553251011 is 11015235512.

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 21553251011 - 2³⁴ = 4373381827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21553251017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535475 + ... + 574316.

It is an arithmetic number, because the mean of its divisors is an integer number (5388595056).

Almost surely, 2^21553251011 is an apocalyptic number.

21553251011 is a deficient number, since it is larger than the sum of its proper divisors (1129213).

21553251011 is a wasteful number, since it uses less digits than its factorization.

21553251011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129212.

The product of its (nonzero) digits is 1500, while the sum is 26.

Adding to 21553251011 its reverse (11015235512), we get a palindrome (32568486523).

The spelling of 21553251011 in words is "twenty-one billion, five hundred fifty-three million, two hundred fifty-one thousand, eleven".