19641639 has 4 divisors (see below), whose sum is σ = 26188856. Its totient is φ = 13094424.

The previous prime is 19641623. The next prime is 19641679. The reversal of 19641639 is 93614691.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 19641639 - 2⁴ = 19641623 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19641597 and 19641606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19641679) 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, 3273604 + ... + 3273609.

It is an arithmetic number, because the mean of its divisors is an integer number (6547214).

Almost surely, 2^19641639 is an apocalyptic number.

19641639 is a deficient number, since it is larger than the sum of its proper divisors (6547217).

19641639 is an equidigital number, since it uses as much as digits as its factorization.

19641639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6547216.

The product of its digits is 34992, while the sum is 39.

The square root of 19641639 is about 4431.8888749607. Note that the first 4 decimals coincide. The cubic root of 19641639 is about 269.8107452891.

The spelling of 19641639 in words is "nineteen million, six hundred forty-one thousand, six hundred thirty-nine".