20856417 has 4 divisors (see below), whose sum is σ = 27808560. Its totient is φ = 13904276.

The previous prime is 20856389. The next prime is 20856439. The reversal of 20856417 is 71465802.

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 20856417 - 2¹¹ = 20854369 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20856457) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3476067 + ... + 3476072.

It is an arithmetic number, because the mean of its divisors is an integer number (6952140).

Almost surely, 2^20856417 is an apocalyptic number.

It is an amenable number.

20856417 is a deficient number, since it is larger than the sum of its proper divisors (6952143).

20856417 is an equidigital number, since it uses as much as digits as its factorization.

20856417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6952142.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 20856417 is about 4566.8826347959. The cubic root of 20856417 is about 275.2621940133.

The spelling of 20856417 in words is "twenty million, eight hundred fifty-six thousand, four hundred seventeen".