638909541 has 12 divisors (see below), whose sum is σ = 940282668. Its totient is φ = 417902784.

The previous prime is 638909507. The next prime is 638909563. The reversal of 638909541 is 145909836.

It is a happy number.

638909541 is a `hidden beast` number, since 638 + 9 + 0 + 9 + 5 + 4 + 1 = 666.

638909541 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 582208641 + 56700900 = 24129^2 + 7530^2 .

It is not a de Polignac number, because 638909541 - 2¹⁸ = 638647397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638909591) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 669240 + ... + 670193.

It is an arithmetic number, because the mean of its divisors is an integer number (78356889).

Almost surely, 2^638909541 is an apocalyptic number.

It is an amenable number.

638909541 is a deficient number, since it is larger than the sum of its proper divisors (301373127).

638909541 is a wasteful number, since it uses less digits than its factorization.

638909541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1339492 (or 1339489 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The square root of 638909541 is about 25276.6600048345. The cubic root of 638909541 is about 861.2841555432.

The spelling of 638909541 in words is "six hundred thirty-eight million, nine hundred nine thousand, five hundred forty-one".