19989397 has 4 divisors (see below), whose sum is σ = 20116876. Its totient is φ = 19861920.

The previous prime is 19989391. The next prime is 19989413. The reversal of 19989397 is 79398991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79398991 = 7 ⋅11342713.

It can be written as a sum of positive squares in 2 ways, for example, as 13608721 + 6380676 = 3689^2 + 2526^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19989397 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 (19989391) 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, 63504 + ... + 63817.

It is an arithmetic number, because the mean of its divisors is an integer number (5029219).

Almost surely, 2^19989397 is an apocalyptic number.

It is an amenable number.

19989397 is a deficient number, since it is larger than the sum of its proper divisors (127479).

19989397 is a wasteful number, since it uses less digits than its factorization.

19989397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127478.

The product of its digits is 1102248, while the sum is 55.

The square root of 19989397 is about 4470.9503464029. The cubic root of 19989397 is about 271.3937848969.

The spelling of 19989397 in words is "nineteen million, nine hundred eighty-nine thousand, three hundred ninety-seven".