638620537 has 4 divisors (see below), whose sum is σ = 652208256. Its totient is φ = 625032820.

The previous prime is 638620531. The next prime is 638620559. The reversal of 638620537 is 735026836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 638620537 - 2¹¹ = 638618489 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 638620537.

It is not an unprimeable number, because it can be changed into a prime (638620531) 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, 6793789 + ... + 6793882.

It is an arithmetic number, because the mean of its divisors is an integer number (163052064).

Almost surely, 2^638620537 is an apocalyptic number.

It is an amenable number.

638620537 is a deficient number, since it is larger than the sum of its proper divisors (13587719).

638620537 is a wasteful number, since it uses less digits than its factorization.

638620537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13587718.

The product of its (nonzero) digits is 181440, while the sum is 40.

The square root of 638620537 is about 25270.9425427703. The cubic root of 638620537 is about 861.1542716860.

The spelling of 638620537 in words is "six hundred thirty-eight million, six hundred twenty thousand, five hundred thirty-seven".