621905 has 8 divisors (see below), whose sum is σ = 772200. Its totient is φ = 480256.

The previous prime is 621893. The next prime is 621913. The reversal of 621905 is 509126.

It can be written as a sum of positive squares in 4 ways, for example, as 200704 + 421201 = 448^2 + 649^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 621905 - 2¹² = 617809 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2000 + ... + 2289.

It is an arithmetic number, because the mean of its divisors is an integer number (96525).

2⁶²¹⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

621905 is a deficient number, since it is larger than the sum of its proper divisors (150295).

621905 is a wasteful number, since it uses less digits than its factorization.

621905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4323.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 621905 is about 788.6095358287. The cubic root of 621905 is about 85.3574337174.

The spelling of 621905 in words is "six hundred twenty-one thousand, nine hundred five".