638665061 has 8 divisors (see below), whose sum is σ = 678628224. Its totient is φ = 598968000.

The previous prime is 638665051. The next prime is 638665063. The reversal of 638665061 is 160566836.

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 638665061 - 2¹⁸ = 638402917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638665063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61565 + ... + 71186.

It is an arithmetic number, because the mean of its divisors is an integer number (84828528).

Almost surely, 2^638665061 is an apocalyptic number.

It is an amenable number.

638665061 is a deficient number, since it is larger than the sum of its proper divisors (39963163).

638665061 is a wasteful number, since it uses less digits than its factorization.

638665061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133051.

The product of its (nonzero) digits is 155520, while the sum is 41.

The square root of 638665061 is about 25271.8234601305. The cubic root of 638665061 is about 861.1742841658.

The spelling of 638665061 in words is "six hundred thirty-eight million, six hundred sixty-five thousand, sixty-one".