20512813 has 4 divisors (see below), whose sum is σ = 20544508. Its totient is φ = 20481120.

The previous prime is 20512771. The next prime is 20512841. The reversal of 20512813 is 31821502.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15069924 + 5442889 = 3882^2 + 2333^2 .

It is a cyclic number.

It is not a de Polignac number, because 20512813 - 2¹⁷ = 20381741 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 (20512883) 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, 14856 + ... + 16177.

It is an arithmetic number, because the mean of its divisors is an integer number (5136127).

Almost surely, 2^20512813 is an apocalyptic number.

It is an amenable number.

20512813 is a deficient number, since it is larger than the sum of its proper divisors (31695).

20512813 is an equidigital number, since it uses as much as digits as its factorization.

20512813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31694.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 20512813 is about 4529.1073071854. The cubic root of 20512813 is about 273.7421918361.

The spelling of 20512813 in words is "twenty million, five hundred twelve thousand, eight hundred thirteen".