19901999 has 8 divisors (see below), whose sum is σ = 21518112. Its totient is φ = 18298080.

The previous prime is 19901963. The next prime is 19902011. The reversal of 19901999 is 99910991.

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 19901999 - 2¹² = 19897903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19901909) 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, 509 + ... + 6329.

It is an arithmetic number, because the mean of its divisors is an integer number (2689764).

Almost surely, 2^19901999 is an apocalyptic number.

19901999 is a deficient number, since it is larger than the sum of its proper divisors (1616113).

19901999 is a wasteful number, since it uses less digits than its factorization.

19901999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6097.

The product of its (nonzero) digits is 59049, while the sum is 47.

The square root of 19901999 is about 4461.1656548485. The cubic root of 19901999 is about 270.9976761192.

The spelling of 19901999 in words is "nineteen million, nine hundred one thousand, nine hundred ninety-nine".