20787813 has 8 divisors (see below), whose sum is σ = 30796800. Its totient is φ = 13858524.

The previous prime is 20787803. The next prime is 20787827. The reversal of 20787813 is 31878702.

It is not a de Polignac number, because 20787813 - 2⁶ = 20787749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20787803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384933 + ... + 384986.

It is an arithmetic number, because the mean of its divisors is an integer number (3849600).

Almost surely, 2^20787813 is an apocalyptic number.

It is an amenable number.

20787813 is a deficient number, since it is larger than the sum of its proper divisors (10008987).

20787813 is an equidigital number, since it uses as much as digits as its factorization.

20787813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 769928 (or 769922 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The square root of 20787813 is about 4559.3654163710. The cubic root of 20787813 is about 274.9600514973.

The spelling of 20787813 in words is "twenty million, seven hundred eighty-seven thousand, eight hundred thirteen".