19665202981 has 4 divisors (see below), whose sum is σ = 19666682092. Its totient is φ = 19663723872.

The previous prime is 19665202967. The next prime is 19665202987. The reversal of 19665202981 is 18920256691.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4862830756 + 14802372225 = 69734^2 + 121665^2 .

It is a cyclic number.

It is not a de Polignac number, because 19665202981 - 2²¹ = 19663105829 is a prime.

It is a super-2 number, since 2×19665202981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19665202987) 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, 719430 + ... + 746263.

It is an arithmetic number, because the mean of its divisors is an integer number (4916670523).

Almost surely, 2^19665202981 is an apocalyptic number.

It is an amenable number.

19665202981 is a deficient number, since it is larger than the sum of its proper divisors (1479111).

19665202981 is a wasteful number, since it uses less digits than its factorization.

19665202981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1479110.

The product of its (nonzero) digits is 466560, while the sum is 49.

The spelling of 19665202981 in words is "nineteen billion, six hundred sixty-five million, two hundred two thousand, nine hundred eighty-one".