20704251 has 4 divisors (see below), whose sum is σ = 27605672. Its totient is φ = 13802832.

The previous prime is 20704219. The next prime is 20704253. The reversal of 20704251 is 15240702.

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

It is not a de Polignac number, because 20704251 - 2⁵ = 20704219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20704253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3450706 + ... + 3450711.

It is an arithmetic number, because the mean of its divisors is an integer number (6901418).

Almost surely, 2^20704251 is an apocalyptic number.

20704251 is a deficient number, since it is larger than the sum of its proper divisors (6901421).

20704251 is an equidigital number, since it uses as much as digits as its factorization.

20704251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6901420.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 20704251 is about 4550.1924135140. The cubic root of 20704251 is about 274.5911323452.

Adding to 20704251 its reverse (15240702), we get a palindrome (35944953).

The spelling of 20704251 in words is "twenty million, seven hundred four thousand, two hundred fifty-one".