21450545 has 4 divisors (see below), whose sum is σ = 25740660. Its totient is φ = 17160432.

The previous prime is 21450523. The next prime is 21450553. The reversal of 21450545 is 54505412.

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 6574096 + 14876449 = 2564^2 + 3857^2 .

It is a cyclic number.

It is not a de Polignac number, because 21450545 - 2²⁴ = 4673329 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2145050 + ... + 2145059.

It is an arithmetic number, because the mean of its divisors is an integer number (6435165).

Almost surely, 2^21450545 is an apocalyptic number.

It is an amenable number.

21450545 is a deficient number, since it is larger than the sum of its proper divisors (4290115).

21450545 is an equidigital number, since it uses as much as digits as its factorization.

21450545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4290114.

The product of its (nonzero) digits is 4000, while the sum is 26.

The square root of 21450545 is about 4631.4733077067. The cubic root of 21450545 is about 277.8515200070.

Adding to 21450545 its reverse (54505412), we get a palindrome (75955957).

The spelling of 21450545 in words is "twenty-one million, four hundred fifty thousand, five hundred forty-five".