640750421 has 8 divisors (see below), whose sum is σ = 644540544. Its totient is φ = 636972160.

The previous prime is 640750391. The next prime is 640750493. The reversal of 640750421 is 124057046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640750421 - 2¹⁴ = 640734037 is a prime.

It is a super-2 number, since 2×640750421² = 821122204023354482, 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 (640750321) 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 7 ways as a sum of consecutive naturals, for example, 119876 + ... + 125106.

It is an arithmetic number, because the mean of its divisors is an integer number (80567568).

Almost surely, 2^640750421 is an apocalyptic number.

It is an amenable number.

640750421 is a deficient number, since it is larger than the sum of its proper divisors (3790123).

640750421 is a wasteful number, since it uses less digits than its factorization.

640750421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5931.

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 640750421 is about 25313.0484335649. The cubic root of 640750421 is about 862.1105638367.

The spelling of 640750421 in words is "six hundred forty million, seven hundred fifty thousand, four hundred twenty-one".