21540845 has 8 divisors (see below), whose sum is σ = 26547864. Its totient is φ = 16766784.

The previous prime is 21540833. The next prime is 21540847. The reversal of 21540845 is 54804512.

It can be written as a sum of positive squares in 4 ways, for example, as 4656964 + 16883881 = 2158^2 + 4109^2 .

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 21540845 - 2¹⁸ = 21278701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540847) 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, 58034 + ... + 58403.

It is an arithmetic number, because the mean of its divisors is an integer number (3318483).

Almost surely, 2^21540845 is an apocalyptic number.

It is an amenable number.

21540845 is a deficient number, since it is larger than the sum of its proper divisors (5007019).

21540845 is a wasteful number, since it uses less digits than its factorization.

21540845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116479.

The product of its (nonzero) digits is 6400, while the sum is 29.

The square root of 21540845 is about 4641.2115875060. The cubic root of 21540845 is about 278.2408631432.

The spelling of 21540845 in words is "twenty-one million, five hundred forty thousand, eight hundred forty-five".