638363749 has 4 divisors (see below), whose sum is σ = 658956160. Its totient is φ = 617771340.

The previous prime is 638363741. The next prime is 638363771. The reversal of 638363749 is 947363836.

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 638363749 - 2³ = 638363741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638363741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10296159 + ... + 10296220.

It is an arithmetic number, because the mean of its divisors is an integer number (164739040).

Almost surely, 2^638363749 is an apocalyptic number.

It is an amenable number.

638363749 is a deficient number, since it is larger than the sum of its proper divisors (20592411).

638363749 is a wasteful number, since it uses less digits than its factorization.

638363749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20592410.

The product of its digits is 1959552, while the sum is 49.

The square root of 638363749 is about 25265.8613350109. The cubic root of 638363749 is about 861.0388334269.

The spelling of 638363749 in words is "six hundred thirty-eight million, three hundred sixty-three thousand, seven hundred forty-nine".