19991123 has 8 divisors (see below), whose sum is σ = 20651328. Its totient is φ = 19341504.

The previous prime is 19991107. The next prime is 19991129. The reversal of 19991123 is 32119991.

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 19991123 - 2⁴ = 19991107 is a prime.

It is a super-2 number, since 2×19991123² = 799289997602258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19991129) 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, 1286 + ... + 6452.

It is an arithmetic number, because the mean of its divisors is an integer number (2581416).

Almost surely, 2^19991123 is an apocalyptic number.

19991123 is a deficient number, since it is larger than the sum of its proper divisors (660205).

19991123 is an equidigital number, since it uses as much as digits as its factorization.

19991123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5293.

The product of its digits is 4374, while the sum is 35.

The square root of 19991123 is about 4471.1433660754. The cubic root of 19991123 is about 271.4015959077.

The spelling of 19991123 in words is "nineteen million, nine hundred ninety-one thousand, one hundred twenty-three".