1016501561 has 4 divisors (see below), whose sum is σ = 1041294324. Its totient is φ = 991708800.

The previous prime is 1016501531. The next prime is 1016501597. The reversal of 1016501561 is 1651056101.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 402403600 + 614097961 = 20060^2 + 24781^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1016501561 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 1016501561.

It is not an unprimeable number, because it can be changed into a prime (1016501531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12396320 + ... + 12396401.

It is an arithmetic number, because the mean of its divisors is an integer number (260323581).

Almost surely, 2^1016501561 is an apocalyptic number.

It is an amenable number.

1016501561 is a deficient number, since it is larger than the sum of its proper divisors (24792763).

1016501561 is an equidigital number, since it uses as much as digits as its factorization.

1016501561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24792762.

The product of its (nonzero) digits is 900, while the sum is 26.

The square root of 1016501561 is about 31882.6216142901. The cubic root of 1016501561 is about 1005.4705389649.

Adding to 1016501561 its reverse (1651056101), we get a palindrome (2667557662).

The spelling of 1016501561 in words is "one billion, sixteen million, five hundred one thousand, five hundred sixty-one".