1221749 has 2 divisors, whose sum is σ = 1221750. Its totient is φ = 1221748.

The previous prime is 1221707. The next prime is 1221751. The reversal of 1221749 is 9471221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 628849 + 592900 = 793^2 + 770^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221749 is a prime.

Together with 1221751, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610874 + 610875.

It is an arithmetic number, because the mean of its divisors is an integer number (610875).

2^1221749 is an apocalyptic number.

It is an amenable number.

1221749 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221749 is an equidigital number, since it uses as much as digits as its factorization.

1221749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 26.

The square root of 1221749 is about 1105.3275532619. The cubic root of 1221749 is about 106.9040103411.

The spelling of 1221749 in words is "one million, two hundred twenty-one thousand, seven hundred forty-nine".