20905807 has 12 divisors (see below), whose sum is σ = 22876464. Its totient is φ = 19094400.

The previous prime is 20905771. The next prime is 20905817. The reversal of 20905807 is 70850902.

It is not a de Polignac number, because 20905807 - 2⁷ = 20905679 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20905817) 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 11 ways as a sum of consecutive naturals, for example, 16807 + ... + 18007.

It is an arithmetic number, because the mean of its divisors is an integer number (1906372).

Almost surely, 2^20905807 is an apocalyptic number.

20905807 is a deficient number, since it is larger than the sum of its proper divisors (1970657).

20905807 is a wasteful number, since it uses less digits than its factorization.

20905807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1330 (or 1317 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 20905807 is about 4572.2868457698. The cubic root of 20905807 is about 275.4793051671.

It can be divided in two parts, 20905 and 807, that added together give a palindrome (21712).

The spelling of 20905807 in words is "twenty million, nine hundred five thousand, eight hundred seven".