20520791 has 4 divisors (see below), whose sum is σ = 21182784. Its totient is φ = 19858800.

The previous prime is 20520769. The next prime is 20520809. The reversal of 20520791 is 19702502.

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

It is a cyclic number.

It is not a de Polignac number, because 20520791 - 2¹⁰ = 20519767 is a prime.

It is a super-2 number, since 2×20520791² = 842205726531362, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20520791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20520701) 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, 330950 + ... + 331011.

It is an arithmetic number, because the mean of its divisors is an integer number (5295696).

Almost surely, 2^20520791 is an apocalyptic number.

20520791 is a deficient number, since it is larger than the sum of its proper divisors (661993).

20520791 is an equidigital number, since it uses as much as digits as its factorization.

20520791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661992.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 20520791 is about 4529.9879690789. The cubic root of 20520791 is about 273.7776758714. Note that the first 3 decimals are identical.

The spelling of 20520791 in words is "twenty million, five hundred twenty thousand, seven hundred ninety-one".