21061385 has 8 divisors (see below), whose sum is σ = 26760456. Its totient is φ = 15857920.

The previous prime is 21061363. The next prime is 21061427. The reversal of 21061385 is 58316012.

It can be written as a sum of positive squares in 4 ways, for example, as 4892944 + 16168441 = 2212^2 + 4021^2 .

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

It is not a de Polignac number, because 21061385 - 2⁸ = 21061129 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 123806 + ... + 123975.

It is an arithmetic number, because the mean of its divisors is an integer number (3345057).

Almost surely, 2^21061385 is an apocalyptic number.

It is an amenable number.

21061385 is a deficient number, since it is larger than the sum of its proper divisors (5699071).

21061385 is a wasteful number, since it uses less digits than its factorization.

21061385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247803.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21061385 is about 4589.2684602233. The cubic root of 21061385 is about 276.1609760713.

Adding to 21061385 its reverse (58316012), we get a palindrome (79377397).

The spelling of 21061385 in words is "twenty-one million, sixty-one thousand, three hundred eighty-five".