20159999 has 4 divisors (see below), whose sum is σ = 20177064. Its totient is φ = 20142936.

The previous prime is 20159957. The next prime is 20160001. The reversal of 20159999 is 99995102.

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 20159999 - 2²⁴ = 3382783 is a prime.

It is a Duffinian number.

20159999 is a modest number, since divided by 9999 gives 2015 as remainder.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20159929) 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, 6617 + ... + 9170.

It is an arithmetic number, because the mean of its divisors is an integer number (5044266).

Almost surely, 2^20159999 is an apocalyptic number.

20159999 is a deficient number, since it is larger than the sum of its proper divisors (17065).

20159999 is a wasteful number, since it uses less digits than its factorization.

20159999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17064.

The product of its (nonzero) digits is 65610, while the sum is 44.

The square root of 20159999 is about 4489.9887527699. The cubic root of 20159999 is about 272.1636801381.

The spelling of 20159999 in words is "twenty million, one hundred fifty-nine thousand, nine hundred ninety-nine".