1221999997 has 2 divisors, whose sum is σ = 1221999998. Its totient is φ = 1221999996.

The previous prime is 1221999983. The next prime is 1222000009. The reversal of 1221999997 is 7999991221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1004319481 + 217680516 = 31691^2 + 14754^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221999997 - 2⁷ = 1221999869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221999907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610999998 + 610999999.

It is an arithmetic number, because the mean of its divisors is an integer number (610999999).

Almost surely, 2^1221999997 is an apocalyptic number.

It is an amenable number.

1221999997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221999997 is an equidigital number, since it uses as much as digits as its factorization.

1221999997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1653372, while the sum is 58.

The square root of 1221999997 is about 34957.1165429874. The cubic root of 1221999997 is about 1069.1133065228.

The spelling of 1221999997 in words is "one billion, two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred ninety-seven".