20499791 has 4 divisors (see below), whose sum is σ = 22076712. Its totient is φ = 18922872.

The previous prime is 20499779. The next prime is 20499799. The reversal of 20499791 is 19799402.

It is a happy number.

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 20499791 - 2¹⁰ = 20498767 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 (20499799) 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, 788441 + ... + 788466.

It is an arithmetic number, because the mean of its divisors is an integer number (5519178).

Almost surely, 2^20499791 is an apocalyptic number.

20499791 is a deficient number, since it is larger than the sum of its proper divisors (1576921).

20499791 is a wasteful number, since it uses less digits than its factorization.

20499791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1576920.

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 20499791 is about 4527.6694888209. The cubic root of 20499791 is about 273.6842536522.

The spelling of 20499791 in words is "twenty million, four hundred ninety-nine thousand, seven hundred ninety-one".