21544601 has 4 divisors (see below), whose sum is σ = 23201892. Its totient is φ = 19887312.

The previous prime is 21544571. The next prime is 21544631. The reversal of 21544601 is 10644512.

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

It is an interprime number because it is at equal distance from previous prime (21544571) and next prime (21544631).

It can be written as a sum of positive squares in 2 ways, for example, as 13987600 + 7557001 = 3740^2 + 2749^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544601 - 2¹⁴ = 21528217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21544631) by changing a digit.

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, 828626 + ... + 828651.

It is an arithmetic number, because the mean of its divisors is an integer number (5800473).

Almost surely, 2^21544601 is an apocalyptic number.

It is an amenable number.

21544601 is a deficient number, since it is larger than the sum of its proper divisors (1657291).

21544601 is a wasteful number, since it uses less digits than its factorization.

21544601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1657290.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21544601 is about 4641.6162055905. The cubic root of 21544601 is about 278.2570341576.

The spelling of 21544601 in words is "twenty-one million, five hundred forty-four thousand, six hundred one".