1561326553 has 2 divisors, whose sum is σ = 1561326554. Its totient is φ = 1561326552.

The previous prime is 1561326497. The next prime is 1561326601. The reversal of 1561326553 is 3556231651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1556539209 + 4787344 = 39453^2 + 2188^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1561326553 is a prime.

It is not a weakly prime, because it can be changed into another prime (1561326353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780663276 + 780663277.

It is an arithmetic number, because the mean of its divisors is an integer number (780663277).

Almost surely, 2^1561326553 is an apocalyptic number.

It is an amenable number.

1561326553 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561326553 is an equidigital number, since it uses as much as digits as its factorization.

1561326553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81000, while the sum is 37.

The square root of 1561326553 is about 39513.6249033166. The cubic root of 1561326553 is about 1160.1066472004.

The spelling of 1561326553 in words is "one billion, five hundred sixty-one million, three hundred twenty-six thousand, five hundred fifty-three".