19660642 has 4 divisors (see below), whose sum is σ = 29490966. Its totient is φ = 9830320.

The previous prime is 19660633. The next prime is 19660643. The reversal of 19660642 is 24606691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24606691 = 19 ⋅1295089.

It can be written as a sum of positive squares in only one way, i.e., 13905441 + 5755201 = 3729^2 + 2399^2 .

It is a junction number, because it is equal to n+sod(n) for n = 19660598 and 19660607.

It is not an unprimeable number, because it can be changed into a prime (19660643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4915159 + ... + 4915162.

Almost surely, 2^19660642 is an apocalyptic number.

19660642 is a deficient number, since it is larger than the sum of its proper divisors (9830324).

19660642 is an equidigital number, since it uses as much as digits as its factorization.

19660642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9830323.

The product of its (nonzero) digits is 15552, while the sum is 34.

The square root of 19660642 is about 4434.0322506721. The cubic root of 19660642 is about 269.8977299000.

It can be divided in two parts, 19660 and 642, that added together give a palindrome (20302).

The spelling of 19660642 in words is "nineteen million, six hundred sixty thousand, six hundred forty-two".