640997945 has 16 divisors (see below), whose sum is σ = 887303808. Its totient is φ = 435431040.

The previous prime is 640997941. The next prime is 640997957. The reversal of 640997945 is 549799046.

640997945 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640997945 - 2² = 640997941 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640997941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 81836 + ... + 89325.

It is an arithmetic number, because the mean of its divisors is an integer number (55456488).

Almost surely, 2^640997945 is an apocalyptic number.

It is an amenable number.

640997945 is a deficient number, since it is larger than the sum of its proper divisors (246305863).

640997945 is a wasteful number, since it uses less digits than its factorization.

640997945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171280.

The product of its (nonzero) digits is 2449440, while the sum is 53.

The square root of 640997945 is about 25317.9372185018. The cubic root of 640997945 is about 862.2215615960.

The spelling of 640997945 in words is "six hundred forty million, nine hundred ninety-seven thousand, nine hundred forty-five".