20851417 has 4 divisors (see below), whose sum is σ = 21948880. Its totient is φ = 19753956.

The previous prime is 20851399. The next prime is 20851433. The reversal of 20851417 is 71415802.

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, and also an emirpimes, since its reverse is a distinct semiprime: 71415802 = 2 ⋅35707901.

It is a cyclic number.

It is not a de Polignac number, because 20851417 - 2⁷ = 20851289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20851477) 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, 548703 + ... + 548740.

It is an arithmetic number, because the mean of its divisors is an integer number (5487220).

Almost surely, 2^20851417 is an apocalyptic number.

It is an amenable number.

20851417 is a deficient number, since it is larger than the sum of its proper divisors (1097463).

20851417 is a wasteful number, since it uses less digits than its factorization.

20851417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1097462.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 20851417 is about 4566.3351826164. The cubic root of 20851417 is about 275.2401956524.

The spelling of 20851417 in words is "twenty million, eight hundred fifty-one thousand, four hundred seventeen".