21100004551 has 4 divisors (see below), whose sum is σ = 21120120000.
Its totient is φ = 21079889104.
The previous prime is 21100004543. The next prime is 21100004557. The reversal of 21100004551 is 15540000112.
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 21100004551 - 23 = 21100004543 is a prime.
It is a super-3 number, since 3×211000045513 (a number of 32 digits) contains 333 as substring.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (21100004557) 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, 10056151 + ... + 10058248.
It is an arithmetic number, because the mean of its divisors is an integer number (5280030000).
Almost surely, 221100004551 is an apocalyptic number.
21100004551 is a deficient number, since it is larger than the sum of its proper divisors (20115449).
21100004551 is a wasteful number, since it uses less digits than its factorization.
21100004551 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 20115448.
The product of its (nonzero) digits is 200, while the sum is 19.
Adding to 21100004551 its reverse (15540000112), we get a palindrome (36640004663).
The spelling of 21100004551 in words is "twenty-one billion, one hundred million, four thousand, five hundred fifty-one".