1506661561 has 2 divisors, whose sum is σ = 1506661562. Its totient is φ = 1506661560.

The previous prime is 1506661549. The next prime is 1506661573. The reversal of 1506661561 is 1651666051.

It is a balanced prime because it is at equal distance from previous prime (1506661549) and next prime (1506661573).

It can be written as a sum of positive squares in only one way, i.e., 951352336 + 555309225 = 30844^2 + 23565^2 .

It is a cyclic number.

It is not a de Polignac number, because 1506661561 - 2⁷ = 1506661433 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1506661561.

It is not a weakly prime, because it can be changed into another prime (1506661501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 753330780 + 753330781.

It is an arithmetic number, because the mean of its divisors is an integer number (753330781).

Almost surely, 2^1506661561 is an apocalyptic number.

It is an amenable number.

1506661561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1506661561 is an equidigital number, since it uses as much as digits as its factorization.

1506661561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 1506661561 is about 38815.7385734189. The cubic root of 1506661561 is about 1146.4063143343.

The spelling of 1506661561 in words is "one billion, five hundred six million, six hundred sixty-one thousand, five hundred sixty-one".