1999638 has 12 divisors (see below), whose sum is σ = 4332588. Its totient is φ = 666540.

The previous prime is 1999633. The next prime is 1999651. The reversal of 1999638 is 8369991.

1999638 is a `hidden beast` number, since 1 + 9 + 9 + 9 + 638 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 1999593 and 1999602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999631) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 55528 + ... + 55563.

It is an arithmetic number, because the mean of its divisors is an integer number (361049).

2^1999638 is an apocalyptic number.

1999638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1999638 is an abundant number, since it is smaller than the sum of its proper divisors (2332950).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1999638 is a wasteful number, since it uses less digits than its factorization.

1999638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111099 (or 111096 counting only the distinct ones).

The product of its digits is 104976, while the sum is 45.

The square root of 1999638 is about 1414.0855702538. The cubic root of 1999638 is about 125.9845030071.

The spelling of 1999638 in words is "one million, nine hundred ninety-nine thousand, six hundred thirty-eight".