621999 has 20 divisors (see below), whose sum is σ = 1062864. Its totient is φ = 355104.

The previous prime is 621997. The next prime is 622009. The reversal of 621999 is 999126.

It is not a de Polignac number, because 621999 - 2¹ = 621997 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

621999 is a modest number, since divided by 999 gives 621 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621997) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 19 + ... + 1115.

2⁶²¹⁹⁹⁹ is an apocalyptic number.

621999 is a deficient number, since it is larger than the sum of its proper divisors (440865).

621999 is a wasteful number, since it uses less digits than its factorization.

621999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1116 (or 1107 counting only the distinct ones).

The product of its digits is 8748, while the sum is 36.

The square root of 621999 is about 788.6691321460. The cubic root of 621999 is about 85.3617340497.

The spelling of 621999 in words is "six hundred twenty-one thousand, nine hundred ninety-nine".