640477 has 2 divisors, whose sum is σ = 640478. Its totient is φ = 640476.

The previous prime is 640463. The next prime is 640483. The reversal of 640477 is 774046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 622521 + 17956 = 789^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 640477 - 2¹⁹ = 116189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320238 + 320239.

It is an arithmetic number, because the mean of its divisors is an integer number (320239).

2⁶⁴⁰⁴⁷⁷ is an apocalyptic number.

It is an amenable number.

640477 is a deficient number, since it is larger than the sum of its proper divisors (1).

640477 is an equidigital number, since it uses as much as digits as its factorization.

640477 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4704, while the sum is 28.

The square root of 640477 is about 800.2980694716. The cubic root of 640477 is about 86.1987919792.

The spelling of 640477 in words is "six hundred forty thousand, four hundred seventy-seven".