20017999 has 4 divisors (see below), whose sum is σ = 20559064. Its totient is φ = 19476936.

The previous prime is 20017997. The next prime is 20018017. The reversal of 20017999 is 99971002.

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 20017999 - 2¹ = 20017997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 541027 = 20017999 / (2 + 0 + 0 + 1 + 7 + 9 + 9 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20017997) 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, 270477 + ... + 270550.

It is an arithmetic number, because the mean of its divisors is an integer number (5139766).

Almost surely, 2^20017999 is an apocalyptic number.

20017999 is a deficient number, since it is larger than the sum of its proper divisors (541065).

20017999 is an equidigital number, since it uses as much as digits as its factorization.

20017999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541064.

The product of its (nonzero) digits is 10206, while the sum is 37.

The square root of 20017999 is about 4474.1478518261. The cubic root of 20017999 is about 271.5231652491.

It can be divided in two parts, 2001 and 7999, that added together give a 4-th power (10000 = 10⁴).

The spelling of 20017999 in words is "twenty million, seventeen thousand, nine hundred ninety-nine".