640369 has 2 divisors, whose sum is σ = 640370. Its totient is φ = 640368.

The previous prime is 640363. The next prime is 640411. The reversal of 640369 is 963046.

640369 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 378225 + 262144 = 615^2 + 512^2 .

It is a cyclic number.

It is not a de Polignac number, because 640369 - 2⁹ = 639857 is a prime.

It is a super-2 number, since 2×640369² = 820144912322, which contains 22 as substring.

640369 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (640363) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320184 + 320185.

It is an arithmetic number, because the mean of its divisors is an integer number (320185).

2⁶⁴⁰³⁶⁹ is an apocalyptic number.

It is an amenable number.

640369 is a deficient number, since it is larger than the sum of its proper divisors (1).

640369 is an equidigital number, since it uses as much as digits as its factorization.

640369 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 640369 is about 800.2305917671. The cubic root of 640369 is about 86.1939466359.

The spelling of 640369 in words is "six hundred forty thousand, three hundred sixty-nine".