638423890 has 16 divisors (see below), whose sum is σ = 1237560408. Its totient is φ = 235725696.

The previous prime is 638423879. The next prime is 638423911. The reversal of 638423890 is 98324836.

It can be written as a sum of positive squares in 4 ways, for example, as 231070401 + 407353489 = 15201^2 + 20183^2 .

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2455347 + ... + 2455606.

Almost surely, 2^638423890 is an apocalyptic number.

638423890 is a deficient number, since it is larger than the sum of its proper divisors (599136518).

638423890 is a wasteful number, since it uses less digits than its factorization.

638423890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4910973.

The product of its (nonzero) digits is 248832, while the sum is 43.

The square root of 638423890 is about 25267.0514702448. The cubic root of 638423890 is about 861.0658724051.

The spelling of 638423890 in words is "six hundred thirty-eight million, four hundred twenty-three thousand, eight hundred ninety".