20851644 has 48 divisors (see below), whose sum is σ = 54222336. Its totient is φ = 6182400.

The previous prime is 20851643. The next prime is 20851679. The reversal of 20851644 is 44615802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20851643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4524 + ... + 7884.

It is an arithmetic number, because the mean of its divisors is an integer number (1129632).

Almost surely, 2^20851644 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 20851644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27111168).

20851644 is an abundant number, since it is smaller than the sum of its proper divisors (33370692).

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

20851644 is a wasteful number, since it uses less digits than its factorization.

20851644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3426 (or 3424 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

The square root of 20851644 is about 4566.3600383675. The cubic root of 20851644 is about 275.2411944542.

The spelling of 20851644 in words is "twenty million, eight hundred fifty-one thousand, six hundred forty-four".