621855 has 24 divisors (see below), whose sum is σ = 1161888. Its totient is φ = 305856.

The previous prime is 621833. The next prime is 621869. The reversal of 621855 is 558126.

It is not a de Polignac number, because 621855 - 2⁹ = 621343 is a prime.

It is a d-powerful number, because it can be written as 6⁷ + 2¹⁰ + 8⁶ + 1 + 5⁴ + 5⁷ .

It is a congruent number.

It is an unprimeable 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 23 ways as a sum of consecutive naturals, for example, 54 + ... + 1116.

It is an arithmetic number, because the mean of its divisors is an integer number (48412).

2⁶²¹⁸⁵⁵ is an apocalyptic number.

621855 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

621855 is a deficient number, since it is larger than the sum of its proper divisors (540033).

621855 is a wasteful number, since it uses less digits than its factorization.

621855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1087 (or 1084 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 621855 is about 788.5778338249. The cubic root of 621855 is about 85.3551461300.

The spelling of 621855 in words is "six hundred twenty-one thousand, eight hundred fifty-five".