639925441 has 32 divisors (see below), whose sum is σ = 716525568. Its totient is φ = 568995840.

The previous prime is 639925423. The next prime is 639925457. The reversal of 639925441 is 144529936.

It is a 4-Lehmer number, since φ(639925441) divides (639925441-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 639925441 - 2⁵ = 639925409 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a deceptive number, since it divides R_639925440.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639925411) 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 31 ways as a sum of consecutive naturals, for example, 5038720 + ... + 5038846.

It is an arithmetic number, because the mean of its divisors is an integer number (22391424).

It is a Poulet number, since it divides 2^639925440-1.

Almost surely, 2^639925441 is an apocalyptic number.

639925441 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

639925441 is a deficient number, since it is larger than the sum of its proper divisors (76600127).

639925441 is a wasteful number, since it uses less digits than its factorization.

639925441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361.

The product of its digits is 233280, while the sum is 43.

The square root of 639925441 is about 25296.7476368011. The cubic root of 639925441 is about 861.7404096098.

The spelling of 639925441 in words is "six hundred thirty-nine million, nine hundred twenty-five thousand, four hundred forty-one".