19965640249651 has 4 divisors (see below), whose sum is σ = 19967775850000. Its totient is φ = 19963504649304.

The previous prime is 19965640249631. The next prime is 19965640249679. The reversal of 19965640249651 is 15694204656991.

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

It is a cyclic number.

It is not a de Polignac number, because 19965640249651 - 2¹⁷ = 19965640118579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19965640249631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1067786151 + ... + 1067804848.

It is an arithmetic number, because the mean of its divisors is an integer number (4991943962500).

Almost surely, 2^{19965640249651} is an apocalyptic number.

19965640249651 is a deficient number, since it is larger than the sum of its proper divisors (2135600349).

19965640249651 is an equidigital number, since it uses as much as digits as its factorization.

19965640249651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2135600348.

The product of its (nonzero) digits is 125971200, while the sum is 67.

The spelling of 19965640249651 in words is "nineteen trillion, nine hundred sixty-five billion, six hundred forty million, two hundred forty-nine thousand, six hundred fifty-one".