638742487 has 4 divisors (see below), whose sum is σ = 660768120. Its totient is φ = 616716856.

The previous prime is 638742457. The next prime is 638742491. The reversal of 638742487 is 784247836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638742487 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 638742487.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638742427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11012773 + ... + 11012830.

It is an arithmetic number, because the mean of its divisors is an integer number (165192030).

Almost surely, 2^638742487 is an apocalyptic number.

638742487 is a deficient number, since it is larger than the sum of its proper divisors (22025633).

638742487 is a wasteful number, since it uses less digits than its factorization.

638742487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22025632.

The product of its digits is 1806336, while the sum is 49.

The square root of 638742487 is about 25273.3552778415. The cubic root of 638742487 is about 861.2090830976.

The spelling of 638742487 in words is "six hundred thirty-eight million, seven hundred forty-two thousand, four hundred eighty-seven".