19999121 has 8 divisors (see below), whose sum is σ = 20913984. Its totient is φ = 19088080.

The previous prime is 19999117. The next prime is 19999127. The reversal of 19999121 is 12199991.

It is a happy number.

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 19999121 - 2² = 19999117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19999127) 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, 17786 + ... + 18876.

It is an arithmetic number, because the mean of its divisors is an integer number (2614248).

Almost surely, 2^19999121 is an apocalyptic number.

It is an amenable number.

19999121 is a deficient number, since it is larger than the sum of its proper divisors (914863).

19999121 is a wasteful number, since it uses less digits than its factorization.

19999121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1911.

The product of its digits is 13122, while the sum is 41.

The square root of 19999121 is about 4472.0376787321. The cubic root of 19999121 is about 271.4377849794.

The spelling of 19999121 in words is "nineteen million, nine hundred ninety-nine thousand, one hundred twenty-one".