1297820221 has 4 divisors (see below), whose sum is σ = 1297892700. Its totient is φ = 1297747744.

The previous prime is 1297820219. The next prime is 1297820243. The reversal of 1297820221 is 1220287921.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1244325625 + 53494596 = 35275^2 + 7314^2 .

It is a cyclic number.

It is not a de Polignac number, because 1297820221 - 2¹ = 1297820219 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 (1297820261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12225 + ... + 52393.

It is an arithmetic number, because the mean of its divisors is an integer number (324473175).

Almost surely, 2^1297820221 is an apocalyptic number.

It is an amenable number.

1297820221 is a deficient number, since it is larger than the sum of its proper divisors (72479).

1297820221 is an equidigital number, since it uses as much as digits as its factorization.

1297820221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72478.

The product of its (nonzero) digits is 8064, while the sum is 34.

The square root of 1297820221 is about 36025.2719767665. The cubic root of 1297820221 is about 1090.7825430124.

The spelling of 1297820221 in words is "one billion, two hundred ninety-seven million, eight hundred twenty thousand, two hundred twenty-one".