21257485 has 12 divisors (see below), whose sum is σ = 26924508. Its totient is φ = 16109568.

The previous prime is 21257479. The next prime is 21257491. The reversal of 21257485 is 58475212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21257479) and next prime (21257491).

It can be written as a sum of positive squares in 2 ways, for example, as 11309769 + 9947716 = 3363^2 + 3154^2 .

It is not a de Polignac number, because 21257485 - 2¹⁹ = 20733197 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21257485.

It is a congruent 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 11 ways as a sum of consecutive naturals, for example, 4084 + ... + 7693.

It is an arithmetic number, because the mean of its divisors is an integer number (2243709).

Almost surely, 2^21257485 is an apocalyptic number.

It is an amenable number.

21257485 is a deficient number, since it is larger than the sum of its proper divisors (5667023).

21257485 is a wasteful number, since it uses less digits than its factorization.

21257485 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11820 (or 11801 counting only the distinct ones).

The product of its digits is 22400, while the sum is 34.

The square root of 21257485 is about 4610.5840194058. The cubic root of 21257485 is about 277.0154300727.

The spelling of 21257485 in words is "twenty-one million, two hundred fifty-seven thousand, four hundred eighty-five".