20804640 has 96 divisors (see below), whose sum is σ = 66407040. Its totient is φ = 5474304.

The previous prime is 20804611. The next prime is 20804653. The reversal of 20804640 is 4640802.

20804640 = T₉₃₉ + T₉₄₀ + ... + T₉₈₃.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20804640.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42477 + ... + 42963.

It is an arithmetic number, because the mean of its divisors is an integer number (691740).

Almost surely, 2^20804640 is an apocalyptic number.

20804640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20804640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33203520).

20804640 is an abundant number, since it is smaller than the sum of its proper divisors (45602400).

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

20804640 is a wasteful number, since it uses less digits than its factorization.

20804640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594 (or 586 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 20804640 is about 4561.2103656815. The cubic root of 20804640 is about 275.0342216365.

The spelling of 20804640 in words is "twenty million, eight hundred four thousand, six hundred forty".