19999890 has 48 divisors (see below), whose sum is σ = 52228800. Its totient is φ = 5309856.

The previous prime is 19999873. The next prime is 19999891. The reversal of 19999890 is 9899991.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19999891) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32001 + ... + 32619.

It is an arithmetic number, because the mean of its divisors is an integer number (1088100).

Almost surely, 2^19999890 is an apocalyptic number.

19999890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19999890 is an abundant number, since it is smaller than the sum of its proper divisors (32228910).

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

19999890 is a wasteful number, since it uses less digits than its factorization.

19999890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991 (or 988 counting only the distinct ones).

The product of its (nonzero) digits is 472392, while the sum is 54.

The square root of 19999890 is about 4472.1236566088. The cubic root of 19999890 is about 271.4412640153.

The spelling of 19999890 in words is "nineteen million, nine hundred ninety-nine thousand, eight hundred ninety".