1240531561 has 2 divisors, whose sum is σ = 1240531562. Its totient is φ = 1240531560.

The previous prime is 1240531499. The next prime is 1240531601. The reversal of 1240531561 is 1651350421.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644195161 + 596336400 = 25381^2 + 24420^2 .

It is a cyclic number.

It is not a de Polignac number, because 1240531561 - 2¹³ = 1240523369 is a prime.

It is not a weakly prime, because it can be changed into another prime (1240531661) 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, 620265780 + 620265781.

It is an arithmetic number, because the mean of its divisors is an integer number (620265781).

Almost surely, 2^1240531561 is an apocalyptic number.

It is an amenable number.

1240531561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1240531561 is an equidigital number, since it uses as much as digits as its factorization.

1240531561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 1240531561 is about 35221.1805736264. The cubic root of 1240531561 is about 1074.4905640279.

Adding to 1240531561 its reverse (1651350421), we get a palindrome (2891881982).

The spelling of 1240531561 in words is "one billion, two hundred forty million, five hundred thirty-one thousand, five hundred sixty-one".