20686257 has 12 divisors (see below), whose sum is σ = 30013620. Its totient is φ = 13729248.

The previous prime is 20686247. The next prime is 20686261. The reversal of 20686257 is 75268602.

20686257 is a `hidden beast` number, since 20 + 6 + 8 + 625 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 13905441 + 6780816 = 3729^2 + 2604^2 .

It is not a de Polignac number, because 20686257 - 2⁴ = 20686241 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20686247) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2958 + ... + 7079.

It is an arithmetic number, because the mean of its divisors is an integer number (2501135).

Almost surely, 2^20686257 is an apocalyptic number.

It is an amenable number.

20686257 is a deficient number, since it is larger than the sum of its proper divisors (9327363).

20686257 is a wasteful number, since it uses less digits than its factorization.

20686257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10272 (or 10269 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 20686257 is about 4548.2147046946. The cubic root of 20686257 is about 274.5115605232.

The spelling of 20686257 in words is "twenty million, six hundred eighty-six thousand, two hundred fifty-seven".