20851993 has 8 divisors (see below), whose sum is σ = 21182112. Its totient is φ = 20524416.

The previous prime is 20851991. The next prime is 20852023. The reversal of 20851993 is 39915802.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20851993 - 2¹ = 20851991 is a prime.

It is a super-2 number, since 2×20851993² = 869611224144098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20851991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21546 + ... + 22492.

It is an arithmetic number, because the mean of its divisors is an integer number (2647764).

Almost surely, 2^20851993 is an apocalyptic number.

It is an amenable number.

20851993 is a deficient number, since it is larger than the sum of its proper divisors (330119).

20851993 is an equidigital number, since it uses as much as digits as its factorization.

20851993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1271.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 20851993 is about 4566.3982524524. The cubic root of 20851993 is about 275.2427300428.

The spelling of 20851993 in words is "twenty million, eight hundred fifty-one thousand, nine hundred ninety-three".