20851668 has 60 divisors (see below), whose sum is σ = 55021120. Its totient is φ = 6885648.

The previous prime is 20851643. The next prime is 20851679. The reversal of 20851668 is 86615802.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nialpdrome in base 9.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 44805 + ... + 45267.

Almost surely, 2^20851668 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20851668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27510560).

20851668 is an abundant number, since it is smaller than the sum of its proper divisors (34169452).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20851668 is a wasteful number, since it uses less digits than its factorization.

20851668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618 (or 607 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 20851668 is about 4566.3626662805. The cubic root of 20851668 is about 275.2413000539.

The spelling of 20851668 in words is "twenty million, eight hundred fifty-one thousand, six hundred sixty-eight".