1971221 has 10 divisors (see below), whose sum is σ = 2302422. Its totient is φ = 1687560.

The previous prime is 1971209. The next prime is 1971241. The reversal of 1971221 is 1221791.

It can be written as a sum of positive squares in only one way, i.e., 1500625 + 470596 = 1225^2 + 686^2 .

It is not a de Polignac number, because 1971221 - 2¹⁸ = 1709077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1971241) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1991 + ... + 2811.

2^1971221 is an apocalyptic number.

It is an amenable number.

1971221 is a deficient number, since it is larger than the sum of its proper divisors (331201).

1971221 is an frugal number, since it uses more digits than its factorization.

1971221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849 (or 828 counting only the distinct ones).

The product of its digits is 252, while the sum is 23.

The square root of 1971221 is about 1404.0017806257. The cubic root of 1971221 is about 125.3848618348.

The spelling of 1971221 in words is "one million, nine hundred seventy-one thousand, two hundred twenty-one".