19890001 has 8 divisors (see below), whose sum is σ = 20120904. Its totient is φ = 19660800.

The previous prime is 19889981. The next prime is 19890007. The reversal of 19890001 is 10009891.

It can be written as a sum of positive squares in 4 ways, for example, as 12787776 + 7102225 = 3576^2 + 2665^2 .

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

It is a 5-Lehmer number, since φ(19890001) divides (19890001-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 19890001 - 2¹¹ = 19887953 is a prime.

It is a super-2 number, since 2×19890001² = 791224279560002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19890007) 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, 49401 + ... + 49801.

It is an arithmetic number, because the mean of its divisors is an integer number (2515113).

Almost surely, 2^19890001 is an apocalyptic number.

It is an amenable number.

19890001 is a deficient number, since it is larger than the sum of its proper divisors (230903).

19890001 is a wasteful number, since it uses less digits than its factorization.

19890001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 19890001 is about 4459.8207363077. The cubic root of 19890001 is about 270.9432078266.

Adding to 19890001 its reverse (10009891), we get a palindrome (29899892).

The spelling of 19890001 in words is "nineteen million, eight hundred ninety thousand, one".