20817820 has 12 divisors (see below), whose sum is σ = 43717464. Its totient is φ = 8327120.

The previous prime is 20817793. The next prime is 20817827. The reversal of 20817820 is 2871802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20817827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 520426 + ... + 520465.

It is an arithmetic number, because the mean of its divisors is an integer number (3643122).

Almost surely, 2^20817820 is an apocalyptic number.

20817820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20817820 is an abundant number, since it is smaller than the sum of its proper divisors (22899644).

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

20817820 is a wasteful number, since it uses less digits than its factorization.

20817820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1040900 (or 1040898 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 20817820 is about 4562.6549288764. The cubic root of 20817820 is about 275.0922885842.

The spelling of 20817820 in words is "twenty million, eight hundred seventeen thousand, eight hundred twenty".