640942905 has 16 divisors (see below), whose sum is σ = 1032303744. Its totient is φ = 339571200.

The previous prime is 640942889. The next prime is 640942961. The reversal of 640942905 is 509249046.

It is not a de Polignac number, because 640942905 - 2⁴ = 640942889 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 139224 + ... + 143753.

It is an arithmetic number, because the mean of its divisors is an integer number (64518984).

Almost surely, 2^640942905 is an apocalyptic number.

It is an amenable number.

640942905 is a deficient number, since it is larger than the sum of its proper divisors (391360839).

640942905 is a wasteful number, since it uses less digits than its factorization.

640942905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283136.

The product of its (nonzero) digits is 77760, while the sum is 39.

The square root of 640942905 is about 25316.8502187772. The cubic root of 640942905 is about 862.1968823525.

The spelling of 640942905 in words is "six hundred forty million, nine hundred forty-two thousand, nine hundred five".