19955991 has 8 divisors (see below), whose sum is σ = 29026944. Its totient is φ = 12094520.

The previous prime is 19955989. The next prime is 19956043.

It is a happy number.

19955991 is nontrivially palindromic in base 10.

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 19955991 - 2¹ = 19955989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19955991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19955951) 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, 302331 + ... + 302396.

It is an arithmetic number, because the mean of its divisors is an integer number (3628368).

Almost surely, 2^19955991 is an apocalyptic number.

19955991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

19955991 is a deficient number, since it is larger than the sum of its proper divisors (9070953).

19955991 is a wasteful number, since it uses less digits than its factorization.

19955991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 604741.

The product of its digits is 164025, while the sum is 48.

The square root of 19955991 is about 4467.2128894871. The cubic root of 19955991 is about 271.2425174375.

The spelling of 19955991 in words is "nineteen million, nine hundred fifty-five thousand, nine hundred ninety-one".