20821764 has 24 divisors (see below), whose sum is σ = 48676320. Its totient is φ = 6927424.

The previous prime is 20821763. The next prime is 20821789. The reversal of 20821764 is 46712802.

It is not an unprimeable number, because it can be changed into a prime (20821763) 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, 6592 + ... + 9224.

It is an arithmetic number, because the mean of its divisors is an integer number (2028180).

Almost surely, 2^20821764 is an apocalyptic number.

It is an amenable number.

20821764 is an abundant number, since it is smaller than the sum of its proper divisors (27854556).

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

20821764 is a wasteful number, since it uses less digits than its factorization.

20821764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3299 (or 3297 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 20821764 is about 4563.0871129094. The cubic root of 20821764 is about 275.1096598472.

The spelling of 20821764 in words is "twenty million, eight hundred twenty-one thousand, seven hundred sixty-four".