1211681 has 4 divisors (see below), whose sum is σ = 1214100. Its totient is φ = 1209264.

The previous prime is 1211677. The next prime is 1211689. The reversal of 1211681 is 1861121.

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 193600 + 1018081 = 440^2 + 1009^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211681 - 2² = 1211677 is a prime.

It is a super-2 number, since 2×1211681² = 2936341691522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1211689) 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, 146 + ... + 1563.

It is an arithmetic number, because the mean of its divisors is an integer number (303525).

2^1211681 is an apocalyptic number.

It is an amenable number.

1211681 is a deficient number, since it is larger than the sum of its proper divisors (2419).

1211681 is an equidigital number, since it uses as much as digits as its factorization.

1211681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2418.

The product of its digits is 96, while the sum is 20.

The square root of 1211681 is about 1100.7638257138. The cubic root of 1211681 is about 106.6095473264.

It can be divided in two parts, 121 and 1681, that multiplied together give a square (203401 = 451²).

The spelling of 1211681 in words is "one million, two hundred eleven thousand, six hundred eighty-one".