19554434121661 has 2 divisors, whose sum is σ = 19554434121662. Its totient is φ = 19554434121660.

The previous prime is 19554434121583. The next prime is 19554434121689. The reversal of 19554434121661 is 16612143445591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19474171832025 + 80262289636 = 4412955^2 + 283306^2 .

It is an emirp because it is prime and its reverse (16612143445591) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19554434121661 - 2¹³ = 19554434113469 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19554434121599 and 19554434121608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19554434121361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9777217060830 + 9777217060831.

It is an arithmetic number, because the mean of its divisors is an integer number (9777217060831).

Almost surely, 2^{19554434121661} is an apocalyptic number.

It is an amenable number.

19554434121661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19554434121661 is an equidigital number, since it uses as much as digits as its factorization.

19554434121661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3110400, while the sum is 52.

The spelling of 19554434121661 in words is "nineteen trillion, five hundred fifty-four billion, four hundred thirty-four million, one hundred twenty-one thousand, six hundred sixty-one".