15552661561 has 2 divisors, whose sum is σ = 15552661562. Its totient is φ = 15552661560.

The previous prime is 15552661513. The next prime is 15552661613. The reversal of 15552661561 is 16516625551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8043399225 + 7509262336 = 89685^2 + 86656^2 .

It is an emirp because it is prime and its reverse (16516625551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15552661561 - 2¹⁷ = 15552530489 is a prime.

It is not a weakly prime, because it can be changed into another prime (15552667561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7776330780 + 7776330781.

It is an arithmetic number, because the mean of its divisors is an integer number (7776330781).

Almost surely, 2^15552661561 is an apocalyptic number.

It is an amenable number.

15552661561 is a deficient number, since it is larger than the sum of its proper divisors (1).

15552661561 is an equidigital number, since it uses as much as digits as its factorization.

15552661561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 270000, while the sum is 43.

The spelling of 15552661561 in words is "fifteen billion, five hundred fifty-two million, six hundred sixty-one thousand, five hundred sixty-one".