640834207 has 4 divisors (see below), whose sum is σ = 690129160. Its totient is φ = 591539256.

The previous prime is 640834189. The next prime is 640834231. The reversal of 640834207 is 702438046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 702438046 = 2 ⋅351219023.

It is a cyclic number.

It is not a de Polignac number, because 640834207 - 2⁷ = 640834079 is a prime.

It is a super-2 number, since 2×640834207² = 821336961722637698, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640834267) 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, 24647457 + ... + 24647482.

It is an arithmetic number, because the mean of its divisors is an integer number (172532290).

Almost surely, 2^640834207 is an apocalyptic number.

640834207 is a deficient number, since it is larger than the sum of its proper divisors (49294953).

640834207 is a wasteful number, since it uses less digits than its factorization.

640834207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49294952.

The product of its (nonzero) digits is 32256, while the sum is 34.

The square root of 640834207 is about 25314.7033757064. The cubic root of 640834207 is about 862.1481393862.

The spelling of 640834207 in words is "six hundred forty million, eight hundred thirty-four thousand, two hundred seven".