20110813 has 4 divisors (see below), whose sum is σ = 21293820. Its totient is φ = 18927808.

The previous prime is 20110807. The next prime is 20110819. The reversal of 20110813 is 31801102.

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

It is an interprime number because it is at equal distance from previous prime (20110807) and next prime (20110819).

It can be written as a sum of positive squares in 2 ways, for example, as 11002489 + 9108324 = 3317^2 + 3018^2 .

It is a cyclic number.

It is not a de Polignac number, because 20110813 - 2⁹ = 20110301 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 (20110819) 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, 591478 + ... + 591511.

It is an arithmetic number, because the mean of its divisors is an integer number (5323455).

Almost surely, 2^20110813 is an apocalyptic number.

It is an amenable number.

20110813 is a deficient number, since it is larger than the sum of its proper divisors (1183007).

20110813 is a wasteful number, since it uses less digits than its factorization.

20110813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1183006.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 20110813 is about 4484.5081112648. The cubic root of 20110813 is about 271.9421598827.

Adding to 20110813 its reverse (31801102), we get a palindrome (51911915).

The spelling of 20110813 in words is "twenty million, one hundred ten thousand, eight hundred thirteen".