19638661 has 12 divisors (see below), whose sum is σ = 22921068. Its totient is φ = 16777152.

The previous prime is 19638653. The next prime is 19638667. The reversal of 19638661 is 16683691.

It can be written as a sum of positive squares in 2 ways, for example, as 16769025 + 2869636 = 4095^2 + 1694^2 .

It is not a de Polignac number, because 19638661 - 2³ = 19638653 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 (19638667) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21955 + ... + 22831.

It is an arithmetic number, because the mean of its divisors is an integer number (1910089).

Almost surely, 2^19638661 is an apocalyptic number.

It is an amenable number.

19638661 is a deficient number, since it is larger than the sum of its proper divisors (3282407).

19638661 is an equidigital number, since it uses as much as digits as its factorization.

19638661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1348 (or 1341 counting only the distinct ones).

The product of its digits is 46656, while the sum is 40.

The square root of 19638661 is about 4431.5528880969. The cubic root of 19638661 is about 269.7971086639.

The spelling of 19638661 in words is "nineteen million, six hundred thirty-eight thousand, six hundred sixty-one".