15545561 has 2 divisors, whose sum is σ = 15545562. Its totient is φ = 15545560.

The previous prime is 15545557. The next prime is 15545573. The reversal of 15545561 is 16554551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12145225 + 3400336 = 3485^2 + 1844^2 .

It is a cyclic number.

It is not a de Polignac number, because 15545561 - 2² = 15545557 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (15545501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7772780 + 7772781.

It is an arithmetic number, because the mean of its divisors is an integer number (7772781).

Almost surely, 2^15545561 is an apocalyptic number.

It is an amenable number.

15545561 is a deficient number, since it is larger than the sum of its proper divisors (1).

15545561 is an equidigital number, since it uses as much as digits as its factorization.

15545561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15000, while the sum is 32.

The square root of 15545561 is about 3942.7859439741. The cubic root of 15545561 is about 249.5756052975.

The spelling of 15545561 in words is "fifteen million, five hundred forty-five thousand, five hundred sixty-one".