1681619398553 has 4 divisors (see below), whose sum is σ = 1682059501668. Its totient is φ = 1681179295440.

The previous prime is 1681619398549. The next prime is 1681619398561. The reversal of 1681619398553 is 3558939161861.

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 1499809260889 + 181810137664 = 1224667^2 + 426392^2 .

It is a cyclic number.

It is not a de Polignac number, because 1681619398553 - 2² = 1681619398549 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1681619398553.

It is not an unprimeable number, because it can be changed into a prime (1681619398513) 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, 220045826 + ... + 220053467.

It is an arithmetic number, because the mean of its divisors is an integer number (420514875417).

Almost surely, 2^{1681619398553} is an apocalyptic number.

It is an amenable number.

1681619398553 is a deficient number, since it is larger than the sum of its proper divisors (440103115).

1681619398553 is an equidigital number, since it uses as much as digits as its factorization.

1681619398553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440103114.

The product of its digits is 41990400, while the sum is 65.

The spelling of 1681619398553 in words is "one trillion, six hundred eighty-one billion, six hundred nineteen million, three hundred ninety-eight thousand, five hundred fifty-three".