638820111 has 8 divisors (see below), whose sum is σ = 860030080. Its totient is φ = 421745112.

The previous prime is 638820097. The next prime is 638820137. The reversal of 638820111 is 111028836.

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

It is not a de Polignac number, because 638820111 - 2⁶ = 638820047 is a prime.

It is a super-2 number, since 2×638820111² = 816182268436104642, 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 (638820181) 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, 1033381 + ... + 1033998.

It is an arithmetic number, because the mean of its divisors is an integer number (107503760).

Almost surely, 2^638820111 is an apocalyptic number.

638820111 is a deficient number, since it is larger than the sum of its proper divisors (221209969).

638820111 is a wasteful number, since it uses less digits than its factorization.

638820111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2067485.

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 638820111 is about 25274.8909196459. The cubic root of 638820111 is about 861.2439681973.

Adding to 638820111 its reverse (111028836), we get a palindrome (749848947).

The spelling of 638820111 in words is "six hundred thirty-eight million, eight hundred twenty thousand, one hundred eleven".