1156561 has 8 divisors (see below), whose sum is σ = 1399680. Its totient is φ = 932928.

The previous prime is 1156553. The next prime is 1156567. The reversal of 1156561 is 1656511.

1156561 = 145² + 146² + ... + 186².

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1156561 - 2³ = 1156553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1156567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4741 + ... + 4978.

It is an arithmetic number, because the mean of its divisors is an integer number (174960).

2^1156561 is an apocalyptic number.

It is an amenable number.

1156561 is a deficient number, since it is larger than the sum of its proper divisors (243119).

1156561 is an equidigital number, since it uses as much as digits as its factorization.

1156561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9743.

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

The square root of 1156561 is about 1075.4352607200. The cubic root of 1156561 is about 104.9678208269.

The spelling of 1156561 in words is "one million, one hundred fifty-six thousand, five hundred sixty-one".