21553400051 has 4 divisors (see below), whose sum is σ = 21567553512. Its totient is φ = 21539246592.

The previous prime is 21553400041. The next prime is 21553400053. The reversal of 21553400051 is 15000435512.

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 21553400051 - 2¹⁰ = 21553399027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21553400053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7074446 + ... + 7077491.

It is an arithmetic number, because the mean of its divisors is an integer number (5391888378).

Almost surely, 2^21553400051 is an apocalyptic number.

21553400051 is a deficient number, since it is larger than the sum of its proper divisors (14153461).

21553400051 is a wasteful number, since it uses less digits than its factorization.

21553400051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14153460.

The product of its (nonzero) digits is 3000, while the sum is 26.

Adding to 21553400051 its reverse (15000435512), we get a palindrome (36553835563).

The spelling of 21553400051 in words is "twenty-one billion, five hundred fifty-three million, four hundred thousand, fifty-one".