1531561 has 2 divisors, whose sum is σ = 1531562. Its totient is φ = 1531560.

The previous prime is 1531549. The next prime is 1531567. The reversal of 1531561 is 1651351.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 921600 + 609961 = 960^2 + 781^2 .

It is a cyclic number.

It is not a de Polignac number, because 1531561 - 2¹¹ = 1529513 is a prime.

1531561 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1531567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 765780 + 765781.

It is an arithmetic number, because the mean of its divisors is an integer number (765781).

2^1531561 is an apocalyptic number.

It is an amenable number.

1531561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1531561 is an equidigital number, since it uses as much as digits as its factorization.

1531561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 450, while the sum is 22.

The square root of 1531561 is about 1237.5625236730. The cubic root of 1531561 is about 115.2687100151.

It can be divided in two parts, 15315 and 61, that added together give a square (15376 = 124²).

The spelling of 1531561 in words is "one million, five hundred thirty-one thousand, five hundred sixty-one".