640037971 has 4 divisors (see below), whose sum is σ = 673724200. Its totient is φ = 606351744.

The previous prime is 640037927. The next prime is 640038001. The reversal of 640037971 is 179730046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640037971 - 2¹³ = 640029779 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640037971.

It is not an unprimeable number, because it can be changed into a prime (640034971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16843086 + ... + 16843123.

It is an arithmetic number, because the mean of its divisors is an integer number (168431050).

Almost surely, 2^640037971 is an apocalyptic number.

640037971 is a deficient number, since it is larger than the sum of its proper divisors (33686229).

640037971 is a wasteful number, since it uses less digits than its factorization.

640037971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33686228.

The product of its (nonzero) digits is 31752, while the sum is 37.

The square root of 640037971 is about 25298.9717379976. The cubic root of 640037971 is about 861.7909186006.

The spelling of 640037971 in words is "six hundred forty million, thirty-seven thousand, nine hundred seventy-one".