19998921 has 8 divisors (see below), whose sum is σ = 26721504. Its totient is φ = 13304480.

The previous prime is 19998917. The next prime is 19998943. The reversal of 19998921 is 12989991.

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 19998921 - 2² = 19998917 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19998991) 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, 5316 + ... + 8261.

It is an arithmetic number, because the mean of its divisors is an integer number (3340188).

Almost surely, 2^19998921 is an apocalyptic number.

It is an amenable number.

19998921 is a deficient number, since it is larger than the sum of its proper divisors (6722583).

19998921 is a wasteful number, since it uses less digits than its factorization.

19998921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14071.

The product of its digits is 104976, while the sum is 48.

The square root of 19998921 is about 4472.0153175051. The cubic root of 19998921 is about 271.4368801440.

The spelling of 19998921 in words is "nineteen million, nine hundred ninety-eight thousand, nine hundred twenty-one".