638676989 has 4 divisors (see below), whose sum is σ = 638964480. Its totient is φ = 638389500.

The previous prime is 638676953. The next prime is 638676991. The reversal of 638676989 is 989676836.

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 a de Polignac number, because none of the positive numbers 2^k-638676989 is a prime.

It is a super-2 number, since 2×638676989² = 815816592556212242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638676589) 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, 140387 + ... + 144864.

It is an arithmetic number, because the mean of its divisors is an integer number (159741120).

Almost surely, 2^638676989 is an apocalyptic number.

It is an amenable number.

638676989 is a deficient number, since it is larger than the sum of its proper divisors (287491).

638676989 is a wasteful number, since it uses less digits than its factorization.

638676989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287490.

The product of its digits is 23514624, while the sum is 62.

The square root of 638676989 is about 25272.0594530798. The cubic root of 638676989 is about 861.1796453603.

The spelling of 638676989 in words is "six hundred thirty-eight million, six hundred seventy-six thousand, nine hundred eighty-nine".