20513811 has 4 divisors (see below), whose sum is σ = 27351752. Its totient is φ = 13675872.

The previous prime is 20513791. The next prime is 20513819. The reversal of 20513811 is 11831502.

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

It is not a de Polignac number, because 20513811 - 2⁹ = 20513299 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20513819) 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, 3418966 + ... + 3418971.

It is an arithmetic number, because the mean of its divisors is an integer number (6837938).

Almost surely, 2^20513811 is an apocalyptic number.

20513811 is a deficient number, since it is larger than the sum of its proper divisors (6837941).

20513811 is an equidigital number, since it uses as much as digits as its factorization.

20513811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6837940.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 20513811 is about 4529.2174820823. The cubic root of 20513811 is about 273.7466311797.

The spelling of 20513811 in words is "twenty million, five hundred thirteen thousand, eight hundred eleven".