1221880997 has 2 divisors, whose sum is σ = 1221880998. Its totient is φ = 1221880996.

The previous prime is 1221880969. The next prime is 1221880999. The reversal of 1221880997 is 7990881221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 838739521 + 383141476 = 28961^2 + 19574^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221880997 - 2¹⁶ = 1221815461 is a prime.

Together with 1221880999, 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 (1221880999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610940498 + 610940499.

It is an arithmetic number, because the mean of its divisors is an integer number (610940499).

Almost surely, 2^1221880997 is an apocalyptic number.

It is an amenable number.

1221880997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221880997 is an equidigital number, since it uses as much as digits as its factorization.

1221880997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 47.

The square root of 1221880997 is about 34955.4144160815. The cubic root of 1221880997 is about 1069.0786014999.

The spelling of 1221880997 in words is "one billion, two hundred twenty-one million, eight hundred eighty thousand, nine hundred ninety-seven".