20857487 has 24 divisors (see below), whose sum is σ = 26117856. Its totient is φ = 16595712.

The previous prime is 20857483. The next prime is 20857511. The reversal of 20857487 is 78475802.

It is not a de Polignac number, because 20857487 - 2² = 20857483 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20857483) 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 23 ways as a sum of consecutive naturals, for example, 285683 + ... + 285755.

It is an arithmetic number, because the mean of its divisors is an integer number (1088244).

Almost surely, 2^20857487 is an apocalyptic number.

20857487 is a deficient number, since it is larger than the sum of its proper divisors (5260369).

20857487 is an frugal number, since it uses more digits than its factorization.

20857487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 125440, while the sum is 41.

The square root of 20857487 is about 4566.9997810379. Note that the first 3 decimals coincide. The cubic root of 20857487 is about 275.2669012059.

The spelling of 20857487 in words is "twenty million, eight hundred fifty-seven thousand, four hundred eighty-seven".