1561820363 has 4 divisors (see below), whose sum is σ = 1563176088. Its totient is φ = 1560464640.

The previous prime is 1561820353. The next prime is 1561820369. The reversal of 1561820363 is 3630281651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3630281651 = 173 ⋅20984287.

It is a cyclic number.

It is not a de Polignac number, because 1561820363 - 2²⁸ = 1293384907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561820369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 676133 + ... + 678438.

It is an arithmetic number, because the mean of its divisors is an integer number (390794022).

Almost surely, 2^1561820363 is an apocalyptic number.

1561820363 is a deficient number, since it is larger than the sum of its proper divisors (1355725).

1561820363 is a wasteful number, since it uses less digits than its factorization.

1561820363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1355724.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 1561820363 is about 39519.8730134599. The cubic root of 1561820363 is about 1160.2289389097.

The spelling of 1561820363 in words is "one billion, five hundred sixty-one million, eight hundred twenty thousand, three hundred sixty-three".