21108545 has 8 divisors (see below), whose sum is σ = 25366824. Its totient is φ = 16862464.

The previous prime is 21108541. The next prime is 21108553. The reversal of 21108545 is 54580112.

It can be written as a sum of positive squares in 4 ways, for example, as 4592449 + 16516096 = 2143^2 + 4064^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21108545 - 2² = 21108541 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21108541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1337 + ... + 6633.

It is an arithmetic number, because the mean of its divisors is an integer number (3170853).

Almost surely, 2^21108545 is an apocalyptic number.

It is an amenable number.

21108545 is a deficient number, since it is larger than the sum of its proper divisors (4258279).

21108545 is an equidigital number, since it uses as much as digits as its factorization.

21108545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6099.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 21108545 is about 4594.4036609771. The cubic root of 21108545 is about 276.3669461110.

Adding to 21108545 its reverse (54580112), we get a palindrome (75688657).

The spelling of 21108545 in words is "twenty-one million, one hundred eight thousand, five hundred forty-five".