1099991612521 has 4 divisors (see below), whose sum is σ = 1099994059732. Its totient is φ = 1099989165312.

The previous prime is 1099991612519. The next prime is 1099991612539. The reversal of 1099991612521 is 1252161999901.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 878184523225 + 221807089296 = 937115^2 + 470964^2 .

It is a cyclic number.

It is not a de Polignac number, because 1099991612521 - 2¹ = 1099991612519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1099991612021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 333576 + ... + 1520281.

It is an arithmetic number, because the mean of its divisors is an integer number (274998514933).

Almost surely, 2^{1099991612521} is an apocalyptic number.

It is an amenable number.

1099991612521 is a deficient number, since it is larger than the sum of its proper divisors (2447211).

1099991612521 is an equidigital number, since it uses as much as digits as its factorization.

1099991612521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2447210.

The product of its (nonzero) digits is 787320, while the sum is 55.

The spelling of 1099991612521 in words is "one trillion, ninety-nine billion, nine hundred ninety-one million, six hundred twelve thousand, five hundred twenty-one".