20519999 has 4 divisors (see below), whose sum is σ = 20547864. Its totient is φ = 20492136.

The previous prime is 20519977. The next prime is 20520029. The reversal of 20519999 is 99991502.

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 20519999 - 2¹² = 20515903 is a prime.

It is a Duffinian number.

20519999 is a modest number, since divided by 9999 gives 2051 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20519959) 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, 12797 + ... + 14310.

It is an arithmetic number, because the mean of its divisors is an integer number (5136966).

Almost surely, 2^20519999 is an apocalyptic number.

20519999 is a deficient number, since it is larger than the sum of its proper divisors (27865).

20519999 is an equidigital number, since it uses as much as digits as its factorization.

20519999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27864.

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

The square root of 20519999 is about 4529.9005507848. The cubic root of 20519999 is about 273.7741536759.

The spelling of 20519999 in words is "twenty million, five hundred nineteen thousand, nine hundred ninety-nine".