1221861 has 4 divisors (see below), whose sum is σ = 1629152. Its totient is φ = 814572.

The previous prime is 1221853. The next prime is 1221863. The reversal of 1221861 is 1681221.

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.

It is not a de Polignac number, because 1221861 - 2³ = 1221853 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221863) 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, 203641 + ... + 203646.

It is an arithmetic number, because the mean of its divisors is an integer number (407288).

2^1221861 is an apocalyptic number.

It is an amenable number.

1221861 is a deficient number, since it is larger than the sum of its proper divisors (407291).

1221861 is an equidigital number, since it uses as much as digits as its factorization.

1221861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407290.

The product of its digits is 192, while the sum is 21.

The square root of 1221861 is about 1105.3782158157. The cubic root of 1221861 is about 106.9072769377.

The spelling of 1221861 in words is "one million, two hundred twenty-one thousand, eight hundred sixty-one".