1321099999 has 4 divisors (see below), whose sum is σ = 1363716160. Its totient is φ = 1278483840.

The previous prime is 1321099993. The next prime is 1321100009. The reversal of 1321099999 is 9999901231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9999901231 = 1583 ⋅6317057.

It is a cyclic number.

It is not a de Polignac number, because 1321099999 - 2¹¹ = 1321097951 is a prime.

It is a Duffinian number.

1321099999 is a modest number, since divided by 99999 gives 13210 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321099993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21308034 + ... + 21308095.

It is an arithmetic number, because the mean of its divisors is an integer number (340929040).

Almost surely, 2^1321099999 is an apocalyptic number.

1321099999 is a deficient number, since it is larger than the sum of its proper divisors (42616161).

1321099999 is an equidigital number, since it uses as much as digits as its factorization.

1321099999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42616160.

The product of its (nonzero) digits is 354294, while the sum is 52.

The square root of 1321099999 is about 36346.9393346950. The cubic root of 1321099999 is about 1097.2659370819.

The spelling of 1321099999 in words is "one billion, three hundred twenty-one million, ninety-nine thousand, nine hundred ninety-nine".