643626 has 40 divisors (see below), whose sum is σ = 1502820. Its totient is φ = 205632.

The previous prime is 643619. The next prime is 643633. The reversal of 643626 is 626346.

643626 = T₂₀ + T₂₁ + ... + T₁₅₆.

It is an interprime number because it is at equal distance from previous prime (643619) and next prime (643633).

It can be written as a sum of positive squares in 2 ways, for example, as 641601 + 2025 = 801^2 + 45^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 643626.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643626.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4630 + ... + 4766.

2⁶⁴³⁶²⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643626, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (751410).

643626 is an abundant number, since it is smaller than the sum of its proper divisors (859194).

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

643626 is a wasteful number, since it uses less digits than its factorization.

643626 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180 (or 171 counting only the distinct ones).

The product of its digits is 5184, while the sum is 27.

The square root of 643626 is about 802.2630491304. The cubic root of 643626 is about 86.3398307929.

The spelling of 643626 in words is "six hundred forty-three thousand, six hundred twenty-six".