19990638 has 28 divisors (see below), whose sum is σ = 44961648. Its totient is φ = 6663060.

The previous prime is 19990637. The next prime is 19990639. The reversal of 19990638 is 83609991.

19990638 is a `hidden beast` number, since 1 + 9 + 9 + 9 + 0 + 638 = 666.

It is an interprime number because it is at equal distance from previous prime (19990637) and next prime (19990639).

It is a junction number, because it is equal to n+sod(n) for n = 19990593 and 19990602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19990637) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 5398 + ... + 8313.

Almost surely, 2^19990638 is an apocalyptic number.

19990638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

19990638 is an abundant number, since it is smaller than the sum of its proper divisors (24971010).

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

19990638 is an equidigital number, since it uses as much as digits as its factorization.

19990638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13731 (or 13716 counting only the distinct ones).

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

The square root of 19990638 is about 4471.0891290602. The cubic root of 19990638 is about 271.3994010863.

The spelling of 19990638 in words is "nineteen million, nine hundred ninety thousand, six hundred thirty-eight".