21354545 has 4 divisors (see below), whose sum is σ = 25625460. Its totient is φ = 17083632.

The previous prime is 21354451. The next prime is 21354551. The reversal of 21354545 is 54545312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6739216 + 14615329 = 2596^2 + 3823^2 .

It is a cyclic number.

It is not a de Polignac number, because 21354545 - 2²⁰ = 20305969 is a prime.

21354545 is a modest number, since divided by 4545 gives 2135 as remainder.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2135450 + ... + 2135459.

It is an arithmetic number, because the mean of its divisors is an integer number (6406365).

Almost surely, 2^21354545 is an apocalyptic number.

It is an amenable number.

21354545 is a deficient number, since it is larger than the sum of its proper divisors (4270915).

21354545 is an equidigital number, since it uses as much as digits as its factorization.

21354545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4270914.

The product of its digits is 12000, while the sum is 29.

The square root of 21354545 is about 4621.0978132907. The cubic root of 21354545 is about 277.4364002180.

Adding to 21354545 its reverse (54545312), we get a palindrome (75899857).

The spelling of 21354545 in words is "twenty-one million, three hundred fifty-four thousand, five hundred forty-five".