21134551 has 4 divisors (see below), whose sum is σ = 21177072. Its totient is φ = 21092032.

The previous prime is 21134527. The next prime is 21134569. The reversal of 21134551 is 15543112.

It is a happy number.

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 21134551 - 2¹⁹ = 20610263 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21134501) 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, 20506 + ... + 21511.

It is an arithmetic number, because the mean of its divisors is an integer number (5294268).

Almost surely, 2^21134551 is an apocalyptic number.

21134551 is a deficient number, since it is larger than the sum of its proper divisors (42521).

21134551 is an equidigital number, since it uses as much as digits as its factorization.

21134551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42520.

The product of its digits is 600, while the sum is 22.

The square root of 21134551 is about 4597.2329721257. The cubic root of 21134551 is about 276.4803954154.

Adding to 21134551 its reverse (15543112), we get a palindrome (36677663).

The spelling of 21134551 in words is "twenty-one million, one hundred thirty-four thousand, five hundred fifty-one".