19695665642 has 4 divisors (see below), whose sum is σ = 29543498466. Its totient is φ = 9847832820.

The previous prime is 19695665629. The next prime is 19695665651. The reversal of 19695665642 is 24656659691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24656659691 = 6317 ⋅3903223.

It can be written as a sum of positive squares in only one way, i.e., 10539280921 + 9156384721 = 102661^2 + 95689^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4923916409 + ... + 4923916412.

Almost surely, 2^19695665642 is an apocalyptic number.

19695665642 is a deficient number, since it is larger than the sum of its proper divisors (9847832824).

19695665642 is an equidigital number, since it uses as much as digits as its factorization.

19695665642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9847832823.

The product of its digits is 20995200, while the sum is 59.

The spelling of 19695665642 in words is "nineteen billion, six hundred ninety-five million, six hundred sixty-five thousand, six hundred forty-two".