20857489 has 3 divisors (see below), whose sum is σ = 20862057. Its totient is φ = 20852922.

The previous prime is 20857483. The next prime is 20857511. The reversal of 20857489 is 98475802.

The square root of 20857489 is 4567.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 20857489 - 2¹⁵ = 20824721 is a prime.

It is a Duffinian 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 (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2284 + ... + 6850.

It is an arithmetic number, because the mean of its divisors is an integer number (6954019).

Almost surely, 2^20857489 is an apocalyptic number.

20857489 is the 4567-th square number.

20857489 is the 2284-th centered octagonal number.

It is an amenable number.

20857489 is a deficient number, since it is larger than the sum of its proper divisors (4568).

20857489 is an frugal number, since it uses more digits than its factorization.

20857489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9134 (or 4567 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 43.

The cubic root of 20857489 is about 275.2669100042.

The spelling of 20857489 in words is "twenty million, eight hundred fifty-seven thousand, four hundred eighty-nine".