20321820 has 48 divisors (see below), whose sum is σ = 63225120. Its totient is φ = 5419008.

The previous prime is 20321759. The next prime is 20321867. The reversal of 20321820 is 2812302.

It is a happy number.

It is a super-2 number, since 2×20321820² = 825952736224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20321793 and 20321802.

It is a congruent number.

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, 18277 + ... + 19356.

It is an arithmetic number, because the mean of its divisors is an integer number (1317190).

Almost surely, 2^20321820 is an apocalyptic number.

20321820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20321820 is an abundant number, since it is smaller than the sum of its proper divisors (42903300).

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

20321820 is a wasteful number, since it uses less digits than its factorization.

20321820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37651 (or 37643 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 20321820 is about 4507.9729369197. The cubic root of 20321820 is about 272.8899447708.

The spelling of 20321820 in words is "twenty million, three hundred twenty-one thousand, eight hundred twenty".