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640628 = 22179421
BaseRepresentation
bin10011100011001110100
31012112202222
42130121310
5131000003
621421512
75305502
oct2343164
91175688
10640628
113a834a
1226a898
13195791
14129672
15c9c38
hex9c674

640628 has 12 divisors (see below), whose sum is σ = 1187172. Its totient is φ = 301440.

The previous prime is 640621. The next prime is 640631. The reversal of 640628 is 826046.

640628 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 357604 + 283024 = 598^2 + 532^2 .

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 640597 and 640606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640621) 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, 4643 + ... + 4778.

It is an arithmetic number, because the mean of its divisors is an integer number (98931).

2640628 is an apocalyptic number.

640628 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

640628 is a deficient number, since it is larger than the sum of its proper divisors (546544).

640628 is a wasteful number, since it uses less digits than its factorization.

640628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9442 (or 9440 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 640628 is about 800.3924037621. The cubic root of 640628 is about 86.2055655739.

The spelling of 640628 in words is "six hundred forty thousand, six hundred twenty-eight".

Divisors: 1 2 4 17 34 68 9421 18842 37684 160157 320314 640628