621685 has 4 divisors (see below), whose sum is σ = 746028. Its totient is φ = 497344.

The previous prime is 621679. The next prime is 621697. The reversal of 621685 is 586126.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 128881 + 492804 = 359^2 + 702^2 .

It is a cyclic number.

It is not a de Polignac number, because 621685 - 2¹³ = 613493 is a prime.

It is a Duffinian number.

621685 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62164 + ... + 62173.

It is an arithmetic number, because the mean of its divisors is an integer number (186507).

2⁶²¹⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

621685 is a deficient number, since it is larger than the sum of its proper divisors (124343).

621685 is a wasteful number, since it uses less digits than its factorization.

621685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124342.

The product of its digits is 2880, while the sum is 28.

The square root of 621685 is about 788.4700374776. The cubic root of 621685 is about 85.3473674157.

The spelling of 621685 in words is "six hundred twenty-one thousand, six hundred eighty-five".