21081485 has 4 divisors (see below), whose sum is σ = 25297788. Its totient is φ = 16865184.

The previous prime is 21081443. The next prime is 21081491. The reversal of 21081485 is 58418012.

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 6135529 + 14945956 = 2477^2 + 3866^2 .

It is a cyclic number.

It is not a de Polignac number, because 21081485 - 2¹⁸ = 20819341 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent 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, 2108144 + ... + 2108153.

It is an arithmetic number, because the mean of its divisors is an integer number (6324447).

Almost surely, 2^21081485 is an apocalyptic number.

It is an amenable number.

21081485 is a deficient number, since it is larger than the sum of its proper divisors (4216303).

21081485 is an equidigital number, since it uses as much as digits as its factorization.

21081485 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4216302.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 21081485 is about 4591.4578294916. The cubic root of 21081485 is about 276.2487998419.

Adding to 21081485 its reverse (58418012), we get a palindrome (79499497).

The spelling of 21081485 in words is "twenty-one million, eighty-one thousand, four hundred eighty-five".