19113721 has 4 divisors (see below), whose sum is σ = 20851344. Its totient is φ = 17376100.

The previous prime is 19113673. The next prime is 19113733. The reversal of 19113721 is 12731191.

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: 12731191 = 11 ⋅1157381.

It is a cyclic number.

It is not a de Polignac number, because 19113721 - 2⁹ = 19113209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19113121) 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, 868795 + ... + 868816.

It is an arithmetic number, because the mean of its divisors is an integer number (5212836).

Almost surely, 2^19113721 is an apocalyptic number.

19113721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19113721 is a deficient number, since it is larger than the sum of its proper divisors (1737623).

19113721 is a wasteful number, since it uses less digits than its factorization.

19113721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1737622.

The product of its digits is 378, while the sum is 25.

The square root of 19113721 is about 4371.9241759207. The cubic root of 19113721 is about 267.3714804647.

The spelling of 19113721 in words is "nineteen million, one hundred thirteen thousand, seven hundred twenty-one".