20851199 has 4 divisors (see below), whose sum is σ = 20863080. Its totient is φ = 20839320.

The previous prime is 20851109. The next prime is 20851211. The reversal of 20851199 is 99115802.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 99115802 = 2 ⋅49557901.

It is a cyclic number.

It is not a de Polignac number, because 20851199 - 2²⁴ = 4073983 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 (20851109) 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 3 ways as a sum of consecutive naturals, for example, 2729 + ... + 7010.

It is an arithmetic number, because the mean of its divisors is an integer number (5215770).

Almost surely, 2^20851199 is an apocalyptic number.

20851199 is a deficient number, since it is larger than the sum of its proper divisors (11881).

20851199 is an equidigital number, since it uses as much as digits as its factorization.

20851199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11880.

The product of its (nonzero) digits is 6480, while the sum is 35.

The square root of 20851199 is about 4566.3113122081. The cubic root of 20851199 is about 275.2392364438.

The spelling of 20851199 in words is "twenty million, eight hundred fifty-one thousand, one hundred ninety-nine".