19964893079861 has 2 divisors, whose sum is σ = 19964893079862. Its totient is φ = 19964893079860.

The previous prime is 19964893079809. The next prime is 19964893079863. The reversal of 19964893079861 is 16897039846991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11011446722500 + 8953446357361 = 3318350^2 + 2992231^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19964893079861 is a prime.

It is a super-2 number, since 2×19964893079861² (a number of 27 digits) contains 22 as substring.

Together with 19964893079863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19964893079863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9982446539930 + 9982446539931.

It is an arithmetic number, because the mean of its divisors is an integer number (9982446539931).

Almost surely, 2^{19964893079861} is an apocalyptic number.

It is an amenable number.

19964893079861 is a deficient number, since it is larger than the sum of its proper divisors (1).

19964893079861 is an equidigital number, since it uses as much as digits as its factorization.

19964893079861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1269789696, while the sum is 80.

The spelling of 19964893079861 in words is "nineteen trillion, nine hundred sixty-four billion, eight hundred ninety-three million, seventy-nine thousand, eight hundred sixty-one".