1213228721 has 2 divisors, whose sum is σ = 1213228722. Its totient is φ = 1213228720.

The previous prime is 1213228711. The next prime is 1213228763. The reversal of 1213228721 is 1278223121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1196122225 + 17106496 = 34585^2 + 4136^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213228721 - 2¹⁴ = 1213212337 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1213228711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606614360 + 606614361.

It is an arithmetic number, because the mean of its divisors is an integer number (606614361).

Almost surely, 2^1213228721 is an apocalyptic number.

It is an amenable number.

1213228721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213228721 is an equidigital number, since it uses as much as digits as its factorization.

1213228721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 29.

The square root of 1213228721 is about 34831.4329449708. The cubic root of 1213228721 is about 1066.5492000310.

The spelling of 1213228721 in words is "one billion, two hundred thirteen million, two hundred twenty-eight thousand, seven hundred twenty-one".