1211561 has 12 divisors (see below), whose sum is σ = 1343952. Its totient is φ = 1091376.

The previous prime is 1211549. The next prime is 1211563. The reversal of 1211561 is 1651121.

It is a de Polignac number, because none of the positive numbers 2^k-1211561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1211563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11270 + ... + 11376.

It is an arithmetic number, because the mean of its divisors is an integer number (111996).

2^1211561 is an apocalyptic number.

It is an amenable number.

1211561 is a deficient number, since it is larger than the sum of its proper divisors (132391).

1211561 is a wasteful number, since it uses less digits than its factorization.

1211561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200 (or 187 counting only the distinct ones).

The product of its digits is 60, while the sum is 17.

The square root of 1211561 is about 1100.7093167590. The cubic root of 1211561 is about 106.6060278170.

Adding to 1211561 its reverse (1651121), we get a palindrome (2862682).

It can be divided in two parts, 121 and 1561, that multiplied together give a palindrome (188881).

The spelling of 1211561 in words is "one million, two hundred eleven thousand, five hundred sixty-one".