20851447 has 4 divisors (see below), whose sum is σ = 21193336. Its totient is φ = 20509560.

The previous prime is 20851433. The next prime is 20851451. The reversal of 20851447 is 74415802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20851447 - 2¹¹ = 20849399 is a prime.

It is a Duffinian number.

It is a congruent 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, 170853 + ... + 170974.

It is an arithmetic number, because the mean of its divisors is an integer number (5298334).

Almost surely, 2^20851447 is an apocalyptic number.

20851447 is a deficient number, since it is larger than the sum of its proper divisors (341889).

20851447 is an equidigital number, since it uses as much as digits as its factorization.

20851447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341888.

The product of its (nonzero) digits is 8960, while the sum is 31.

The square root of 20851447 is about 4566.3384675252. The cubic root of 20851447 is about 275.2403276530.

The spelling of 20851447 in words is "twenty million, eight hundred fifty-one thousand, four hundred forty-seven".