621820 has 12 divisors (see below), whose sum is σ = 1305864. Its totient is φ = 248720.

The previous prime is 621799. The next prime is 621821. The reversal of 621820 is 28126.

It is a happy number.

It is a super-2 number, since 2×621820² = 773320224800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621821) by changing a digit.

621820 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 3 ways as a sum of consecutive naturals, for example, 15526 + ... + 15565.

It is an arithmetic number, because the mean of its divisors is an integer number (108822).

2⁶²¹⁸²⁰ is an apocalyptic number.

It is an amenable number.

621820 is an abundant number, since it is smaller than the sum of its proper divisors (684044).

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

621820 is a wasteful number, since it uses less digits than its factorization.

621820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31100 (or 31098 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 621820 is about 788.5556416639. Note that the first 3 decimals coincide. The cubic root of 621820 is about 85.3535447459.

Adding to 621820 its reverse (28126), we get a palindrome (649946).

It can be divided in two parts, 621 and 820, that added together give a palindrome (1441).

The spelling of 621820 in words is "six hundred twenty-one thousand, eight hundred twenty".