1221598397 has 2 divisors, whose sum is σ = 1221598398. Its totient is φ = 1221598396.

The previous prime is 1221598387. The next prime is 1221598421. The reversal of 1221598397 is 7938951221.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1187422681 + 34175716 = 34459^2 + 5846^2 .

It is an emirp because it is prime and its reverse (7938951221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221598397 - 2³⁰ = 147856573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221598387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610799198 + 610799199.

It is an arithmetic number, because the mean of its divisors is an integer number (610799199).

Almost surely, 2^1221598397 is an apocalyptic number.

It is an amenable number.

1221598397 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221598397 is an equidigital number, since it uses as much as digits as its factorization.

1221598397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 47.

The square root of 1221598397 is about 34951.3718900990. The cubic root of 1221598397 is about 1068.9961753312.

The spelling of 1221598397 in words is "one billion, two hundred twenty-one million, five hundred ninety-eight thousand, three hundred ninety-seven".