19940399 has 4 divisors (see below), whose sum is σ = 20012664. Its totient is φ = 19868136.

The previous prime is 19940383. The next prime is 19940411. The reversal of 19940399 is 99304991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99304991 = 773 ⋅128467.

It is a cyclic number.

It is not a de Polignac number, because 19940399 - 2⁴ = 19940383 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 (19940359) 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, 35717 + ... + 36270.

It is an arithmetic number, because the mean of its divisors is an integer number (5003166).

Almost surely, 2^19940399 is an apocalyptic number.

19940399 is a deficient number, since it is larger than the sum of its proper divisors (72265).

19940399 is an equidigital number, since it uses as much as digits as its factorization.

19940399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72264.

The product of its (nonzero) digits is 78732, while the sum is 44.

The square root of 19940399 is about 4465.4673887511. The cubic root of 19940399 is about 271.1718566976.

The spelling of 19940399 in words is "nineteen million, nine hundred forty thousand, three hundred ninety-nine".