621385 has 4 divisors (see below), whose sum is σ = 745668. Its totient is φ = 497104.

The previous prime is 621371. The next prime is 621389. The reversal of 621385 is 583126.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 583126 = 2 ⋅291563.

It can be written as a sum of positive squares in 2 ways, for example, as 207936 + 413449 = 456^2 + 643^2 .

It is a cyclic number.

It is not a de Polignac number, because 621385 - 2⁵ = 621353 is a prime.

It is a super-2 number, since 2×621385² = 772238636450, which contains 22 as substring.

It is a Duffinian number.

621385 is a lucky number.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621389) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 62134 + ... + 62143.

It is an arithmetic number, because the mean of its divisors is an integer number (186417).

2⁶²¹³⁸⁵ is an apocalyptic number.

It is an amenable number.

621385 is a deficient number, since it is larger than the sum of its proper divisors (124283).

621385 is a wasteful number, since it uses less digits than its factorization.

621385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124282.

The product of its digits is 1440, while the sum is 25.

The square root of 621385 is about 788.2797726696. The cubic root of 621385 is about 85.3336368126. Note that the first 3 decimals are identical.

The spelling of 621385 in words is "six hundred twenty-one thousand, three hundred eighty-five".