621684 has 36 divisors (see below), whose sum is σ = 1796704. Its totient is φ = 177552.

The previous prime is 621679. The next prime is 621697. The reversal of 621684 is 486126.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

621684 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 11 ways as a sum of consecutive naturals, for example, 982 + ... + 1485.

2⁶²¹⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

621684 is an abundant number, since it is smaller than the sum of its proper divisors (1175020).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

621684 is a wasteful number, since it uses less digits than its factorization.

621684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2484 (or 2479 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 621684 is about 788.4694033379. The cubic root of 621684 is about 85.3473216543.

The spelling of 621684 in words is "six hundred twenty-one thousand, six hundred eighty-four".