1561035121 has 4 divisors (see below), whose sum is σ = 1561126912. Its totient is φ = 1560943332.

The previous prime is 1561035109. The next prime is 1561035127. The reversal of 1561035121 is 1215301651.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1215301651 = 97 ⋅12528883.

It is a cyclic number.

It is not a de Polignac number, because 1561035121 - 2²¹ = 1558937969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561035127) 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, 12081 + ... + 57166.

It is an arithmetic number, because the mean of its divisors is an integer number (390281728).

Almost surely, 2^1561035121 is an apocalyptic number.

It is an amenable number.

1561035121 is a deficient number, since it is larger than the sum of its proper divisors (91791).

1561035121 is an equidigital number, since it uses as much as digits as its factorization.

1561035121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91790.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 1561035121 is about 39509.9369905850. The cubic root of 1561035121 is about 1160.0344621648.

Adding to 1561035121 its reverse (1215301651), we get a palindrome (2776336772).

The spelling of 1561035121 in words is "one billion, five hundred sixty-one million, thirty-five thousand, one hundred twenty-one".