1561287061 has 4 divisors (see below), whose sum is σ = 1565220172. Its totient is φ = 1557353952.

The previous prime is 1561287047. The next prime is 1561287067. The reversal of 1561287061 is 1607821651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1607821651 = 127 ⋅12660013.

It can be written as a sum of positive squares in 2 ways, for example, as 728676036 + 832611025 = 26994^2 + 28855^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561287061 - 2⁷ = 1561286933 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561287061.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561287067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1965960 + ... + 1966753.

It is an arithmetic number, because the mean of its divisors is an integer number (391305043).

Almost surely, 2^1561287061 is an apocalyptic number.

It is an amenable number.

1561287061 is a deficient number, since it is larger than the sum of its proper divisors (3933111).

1561287061 is an equidigital number, since it uses as much as digits as its factorization.

1561287061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3933110.

The product of its (nonzero) digits is 20160, while the sum is 37.

The square root of 1561287061 is about 39513.1251737951. The cubic root of 1561287061 is about 1160.0968659201.

The spelling of 1561287061 in words is "one billion, five hundred sixty-one million, two hundred eighty-seven thousand, sixty-one".