638940919 has 8 divisors (see below), whose sum is σ = 641520000. Its totient is φ = 636367872.

The previous prime is 638940881. The next prime is 638940923. The reversal of 638940919 is 919049836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 638940919 - 2⁷ = 638940791 is a prime.

It is a super-2 number, since 2×638940919² = 816490995945129122, 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 (638940959) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 362362 + ... + 364120.

It is an arithmetic number, because the mean of its divisors is an integer number (80190000).

Almost surely, 2^638940919 is an apocalyptic number.

638940919 is a deficient number, since it is larger than the sum of its proper divisors (2579081).

638940919 is a wasteful number, since it uses less digits than its factorization.

638940919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3017.

The product of its (nonzero) digits is 419904, while the sum is 49.

The square root of 638940919 is about 25277.2806883968. The cubic root of 638940919 is about 861.2982550519.

The spelling of 638940919 in words is "six hundred thirty-eight million, nine hundred forty thousand, nine hundred nineteen".