20655257 has 4 divisors (see below), whose sum is σ = 23606016. Its totient is φ = 17704500.

The previous prime is 20655241. The next prime is 20655259. The reversal of 20655257 is 75255602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20655257 - 2⁴ = 20655241 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20655259) 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 3 ways as a sum of consecutive naturals, for example, 1475369 + ... + 1475382.

It is an arithmetic number, because the mean of its divisors is an integer number (5901504).

Almost surely, 2^20655257 is an apocalyptic number.

It is an amenable number.

20655257 is a deficient number, since it is larger than the sum of its proper divisors (2950759).

20655257 is an equidigital number, since it uses as much as digits as its factorization.

20655257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2950758.

The product of its (nonzero) digits is 21000, while the sum is 32.

The square root of 20655257 is about 4544.8054963882. The cubic root of 20655257 is about 274.3743661721.

The spelling of 20655257 in words is "twenty million, six hundred fifty-five thousand, two hundred fifty-seven".