20821306 has 16 divisors (see below), whose sum is σ = 34993440. Its totient is φ = 9208080.

The previous prime is 20821291. The next prime is 20821309. The reversal of 20821306 is 60312802.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (20821309) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11976 + ... + 13603.

It is an arithmetic number, because the mean of its divisors is an integer number (2187090).

Almost surely, 2^20821306 is an apocalyptic number.

20821306 is a deficient number, since it is larger than the sum of its proper divisors (14172134).

20821306 is a wasteful number, since it uses less digits than its factorization.

20821306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25629.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 20821306 is about 4563.0369273106. The cubic root of 20821306 is about 275.1076427086.

The spelling of 20821306 in words is "twenty million, eight hundred twenty-one thousand, three hundred six".