19668993 has 4 divisors (see below), whose sum is σ = 26225328. Its totient is φ = 13112660.

The previous prime is 19668977. The next prime is 19668997. The reversal of 19668993 is 39986691.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39986691 = 3 ⋅13328897.

It is a cyclic number.

It is not a de Polignac number, because 19668993 - 2⁴ = 19668977 is a prime.

It is a super-3 number, since 3×19668993³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (19668997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3278163 + ... + 3278168.

It is an arithmetic number, because the mean of its divisors is an integer number (6556332).

It is a Proth number, since it is equal to 2401 ⋅ 2¹³ + 1 and 2401 < 2¹³.

Almost surely, 2^19668993 is an apocalyptic number.

It is an amenable number.

19668993 is a deficient number, since it is larger than the sum of its proper divisors (6556335).

19668993 is an equidigital number, since it uses as much as digits as its factorization.

19668993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6556334.

The product of its digits is 629856, while the sum is 51.

The square root of 19668993 is about 4434.9738443423. The cubic root of 19668993 is about 269.9359381623.

The spelling of 19668993 in words is "nineteen million, six hundred sixty-eight thousand, nine hundred ninety-three".