621659 has 4 divisors (see below), whose sum is σ = 624240. Its totient is φ = 619080.

The previous prime is 621641. The next prime is 621671. The reversal of 621659 is 956126.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 956126 = 2 ⋅478063.

It is a cyclic number.

It is not a de Polignac number, because 621659 - 2¹⁶ = 556123 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (621619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 887 + ... + 1424.

It is an arithmetic number, because the mean of its divisors is an integer number (156060).

2⁶²¹⁶⁵⁹ is an apocalyptic number.

621659 is a deficient number, since it is larger than the sum of its proper divisors (2581).

621659 is a wasteful number, since it uses less digits than its factorization.

621659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2580.

The product of its digits is 3240, while the sum is 29.

The square root of 621659 is about 788.4535496781. The cubic root of 621659 is about 85.3461776049.

The spelling of 621659 in words is "six hundred twenty-one thousand, six hundred fifty-nine".