1563331661 has 2 divisors, whose sum is σ = 1563331662. Its totient is φ = 1563331660.

The previous prime is 1563331633. The next prime is 1563331697. The reversal of 1563331661 is 1661333651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1446280900 + 117050761 = 38030^2 + 10819^2 .

It is a cyclic number.

It is not a de Polignac number, because 1563331661 - 2¹⁴ = 1563315277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1563331261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 781665830 + 781665831.

It is an arithmetic number, because the mean of its divisors is an integer number (781665831).

Almost surely, 2^1563331661 is an apocalyptic number.

It is an amenable number.

1563331661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1563331661 is an equidigital number, since it uses as much as digits as its factorization.

1563331661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29160, while the sum is 35.

The square root of 1563331661 is about 39538.9891246602. The cubic root of 1563331661 is about 1160.6030507353.

The spelling of 1563331661 in words is "one billion, five hundred sixty-three million, three hundred thirty-one thousand, six hundred sixty-one".