21354547 has 4 divisors (see below), whose sum is σ = 21365136. Its totient is φ = 21343960.

The previous prime is 21354451. The next prime is 21354551. The reversal of 21354547 is 74545312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21354547 - 2¹⁵ = 21321779 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21354577) 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, 1228 + ... + 6649.

It is an arithmetic number, because the mean of its divisors is an integer number (5341284).

Almost surely, 2^21354547 is an apocalyptic number.

21354547 is a deficient number, since it is larger than the sum of its proper divisors (10589).

21354547 is an equidigital number, since it uses as much as digits as its factorization.

21354547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10588.

The product of its digits is 16800, while the sum is 31.

The square root of 21354547 is about 4621.0980296895. The cubic root of 21354547 is about 277.4364088792.

Adding to 21354547 its reverse (74545312), we get a palindrome (95899859).

The spelling of 21354547 in words is "twenty-one million, three hundred fifty-four thousand, five hundred forty-seven".