19888991 has 8 divisors (see below), whose sum is σ = 21141120. Its totient is φ = 18657432.

The previous prime is 19888969. The next prime is 19889027. The reversal of 19888991 is 19988891.

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 19888991 - 2⁶ = 19888927 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 (19888901) 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, 3125 + ... + 7038.

It is an arithmetic number, because the mean of its divisors is an integer number (2642640).

Almost surely, 2^19888991 is an apocalyptic number.

19888991 is a deficient number, since it is larger than the sum of its proper divisors (1252129).

19888991 is a wasteful number, since it uses less digits than its factorization.

19888991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10285.

The product of its digits is 373248, while the sum is 53.

The square root of 19888991 is about 4459.7075016194. The cubic root of 19888991 is about 270.9386216483.

The spelling of 19888991 in words is "nineteen million, eight hundred eighty-eight thousand, nine hundred ninety-one".