21541385 has 4 divisors (see below), whose sum is σ = 25849668. Its totient is φ = 17233104.

The previous prime is 21541379. The next prime is 21541391. The reversal of 21541385 is 58314512.

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 (21541379) and next prime (21541391).

It can be written as a sum of positive squares in 2 ways, for example, as 10445824 + 11095561 = 3232^2 + 3331^2 .

It is a cyclic number.

It is not a de Polignac number, because 21541385 - 2⁸ = 21541129 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2154134 + ... + 2154143.

It is an arithmetic number, because the mean of its divisors is an integer number (6462417).

Almost surely, 2^21541385 is an apocalyptic number.

It is an amenable number.

21541385 is a deficient number, since it is larger than the sum of its proper divisors (4308283).

21541385 is an equidigital number, since it uses as much as digits as its factorization.

21541385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4308282.

The product of its digits is 4800, while the sum is 29.

The square root of 21541385 is about 4641.2697616062. The cubic root of 21541385 is about 278.2431881651.

Adding to 21541385 its reverse (58314512), we get a palindrome (79855897).

The spelling of 21541385 in words is "twenty-one million, five hundred forty-one thousand, three hundred eighty-five".