640720270 has 16 divisors (see below), whose sum is σ = 1169096400. Its totient is φ = 252777024.

The previous prime is 640720217. The next prime is 640720273. The reversal of 640720270 is 72027046.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640720273) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 438120 + ... + 439579.

It is an arithmetic number, because the mean of its divisors is an integer number (73068525).

Almost surely, 2^640720270 is an apocalyptic number.

640720270 is a deficient number, since it is larger than the sum of its proper divisors (528376130).

640720270 is a wasteful number, since it uses less digits than its factorization.

640720270 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 877779.

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

The square root of 640720270 is about 25312.4528641536. The cubic root of 640720270 is about 862.0970412011.

The spelling of 640720270 in words is "six hundred forty million, seven hundred twenty thousand, two hundred seventy".