1156561001 has 4 divisors (see below), whose sum is σ = 1156739412. Its totient is φ = 1156382592.

The previous prime is 1156560997. The next prime is 1156561019. The reversal of 1156561001 is 1001656511.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1001656511 = 59 ⋅16977229.

It can be written as a sum of positive squares in 2 ways, for example, as 616230976 + 540330025 = 24824^2 + 23245^2 .

It is a cyclic number.

It is not a de Polignac number, because 1156561001 - 2² = 1156560997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1156561801) 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, 79100 + ... + 92573.

It is an arithmetic number, because the mean of its divisors is an integer number (289184853).

Almost surely, 2^1156561001 is an apocalyptic number.

It is an amenable number.

1156561001 is a deficient number, since it is larger than the sum of its proper divisors (178411).

1156561001 is an equidigital number, since it uses as much as digits as its factorization.

1156561001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178410.

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

The square root of 1156561001 is about 34008.2490140260. The cubic root of 1156561001 is about 1049.6782085719.

It can be divided in two parts, 1156 and 561001, that multiplied together give a square (648517156 = 25466²).

The spelling of 1156561001 in words is "one billion, one hundred fifty-six million, five hundred sixty-one thousand, one".