1213121999 has 2 divisors, whose sum is σ = 1213122000. Its totient is φ = 1213121998.

The previous prime is 1213121971. The next prime is 1213122017. The reversal of 1213121999 is 9991213121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1213121999 - 2¹² = 1213117903 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1213121909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606560999 + 606561000.

It is an arithmetic number, because the mean of its divisors is an integer number (606561000).

Almost surely, 2^1213121999 is an apocalyptic number.

1213121999 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213121999 is an equidigital number, since it uses as much as digits as its factorization.

1213121999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748, while the sum is 38.

The square root of 1213121999 is about 34829.9009329628. The cubic root of 1213121999 is about 1066.5179260156.

The spelling of 1213121999 in words is "one billion, two hundred thirteen million, one hundred twenty-one thousand, nine hundred ninety-nine".