20405723 has 8 divisors (see below), whose sum is σ = 22020768. Its totient is φ = 18797184.

The previous prime is 20405713. The next prime is 20405743. The reversal of 20405723 is 32750402.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20405723 - 2²⁰ = 19357147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20405713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6386 + ... + 9032.

It is an arithmetic number, because the mean of its divisors is an integer number (2752596).

Almost surely, 2^20405723 is an apocalyptic number.

20405723 is a deficient number, since it is larger than the sum of its proper divisors (1615045).

20405723 is a wasteful number, since it uses less digits than its factorization.

20405723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3253.

The product of its (nonzero) digits is 1680, while the sum is 23.

The square root of 20405723 is about 4517.2694185758. The cubic root of 20405723 is about 273.2649906800.

The spelling of 20405723 in words is "twenty million, four hundred five thousand, seven hundred twenty-three".