1563490681 has 3 divisors (see below), whose sum is σ = 1563530223. Its totient is φ = 1563451140.

The previous prime is 1563490667. The next prime is 1563490723. The reversal of 1563490681 is 1860943651.

The square root of 1563490681 is 39541.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 9554281 + 1553936400 = 3091^2 + 39420^2 .

It is not a de Polignac number, because 1563490681 - 2²⁵ = 1529936249 is a prime.

It is a super-2 number, since 2×1563490681² = 4889006219147687522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1563490651) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 19771 + ... + 59311.

It is an arithmetic number, because the mean of its divisors is an integer number (521176741).

Almost surely, 2^1563490681 is an apocalyptic number.

1563490681 is the 39541-st square number.

1563490681 is the 19771-st centered octagonal number.

It is an amenable number.

1563490681 is a deficient number, since it is larger than the sum of its proper divisors (39542).

1563490681 is an frugal number, since it uses more digits than its factorization.

1563490681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79082 (or 39541 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 43.

The cubic root of 1563490681 is about 1160.6424010631.

The spelling of 1563490681 in words is "one billion, five hundred sixty-three million, four hundred ninety thousand, six hundred eighty-one".