640719 has 6 divisors (see below), whose sum is σ = 925496. Its totient is φ = 427140.

The previous prime is 640691. The next prime is 640727. The reversal of 640719 is 917046.

640719 is a `hidden beast` number, since 640 + 7 + 19 = 666.

It is not a de Polignac number, because 640719 - 2⁵ = 640687 is a prime.

It is a super-2 number, since 2×640719² = 821041673922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640692 and 640701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640019) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35587 + ... + 35604.

2⁶⁴⁰⁷¹⁹ is an apocalyptic number.

640719 is a deficient number, since it is larger than the sum of its proper divisors (284777).

640719 is a wasteful number, since it uses less digits than its factorization.

640719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71197 (or 71194 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 640719 is about 800.4492488597. The cubic root of 640719 is about 86.2096471601.

The spelling of 640719 in words is "six hundred forty thousand, seven hundred nineteen".