15575544557561 has 2 divisors, whose sum is σ = 15575544557562. Its totient is φ = 15575544557560.

The previous prime is 15575544557539. The next prime is 15575544557563. The reversal of 15575544557561 is 16575544557551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15567909293161 + 7635264400 = 3945619^2 + 87380^2 .

It is a cyclic number.

It is not a de Polignac number, because 15575544557561 - 2¹⁸ = 15575544295417 is a prime.

Together with 15575544557563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (15575544557563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7787772278780 + 7787772278781.

It is an arithmetic number, because the mean of its divisors is an integer number (7787772278781).

Almost surely, 2^{15575544557561} is an apocalyptic number.

It is an amenable number.

15575544557561 is a deficient number, since it is larger than the sum of its proper divisors (1).

15575544557561 is an equidigital number, since it uses as much as digits as its factorization.

15575544557561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 367500000, while the sum is 65.

The spelling of 15575544557561 in words is "fifteen trillion, five hundred seventy-five billion, five hundred forty-four million, five hundred fifty-seven thousand, five hundred sixty-one".