20201999 has 4 divisors (see below), whose sum is σ = 20280864. Its totient is φ = 20123136.

The previous prime is 20201983. The next prime is 20202011. The reversal of 20201999 is 99910202.

20201999 = T₂₆₁ + T₂₆₂ + ... + T₅₁₇.

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 20201999 - 2⁴ = 20201983 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 (20201939) 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, 39047 + ... + 39560.

It is an arithmetic number, because the mean of its divisors is an integer number (5070216).

Almost surely, 2^20201999 is an apocalyptic number.

20201999 is a deficient number, since it is larger than the sum of its proper divisors (78865).

20201999 is an equidigital number, since it uses as much as digits as its factorization.

20201999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78864.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 20201999 is about 4494.6633911785. The cubic root of 20201999 is about 272.3525516030.

The spelling of 20201999 in words is "twenty million, two hundred one thousand, nine hundred ninety-nine".