20689857 has 16 divisors (see below), whose sum is σ = 31985280. Its totient is φ = 13193136.

The previous prime is 20689849. The next prime is 20689873. The reversal of 20689857 is 75898602.

It is not a de Polignac number, because 20689857 - 2³ = 20689849 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20689807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16038 + ... + 17279.

It is an arithmetic number, because the mean of its divisors is an integer number (1999080).

Almost surely, 2^20689857 is an apocalyptic number.

20689857 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

20689857 is a deficient number, since it is larger than the sum of its proper divisors (11295423).

20689857 is a wasteful number, since it uses less digits than its factorization.

20689857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33349 (or 33343 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The square root of 20689857 is about 4548.6104471586. The cubic root of 20689857 is about 274.5274838855.

The spelling of 20689857 in words is "twenty million, six hundred eighty-nine thousand, eight hundred fifty-seven".