99851537521 has 4 divisors (see below), whose sum is σ = 99852207844.
Its totient is φ = 99850867200.
The previous prime is 99851537491. The next prime is 99851537537. The reversal of 99851537521 is 12573515899.
It is a happy number.
99851537521 is a nontrivial binomial coefficient, being equal to C(446882, 2).
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12573515899 = 7 ⋅1796216557.
It can be written as a sum of positive squares in 2 ways, for example, as 51092273296 + 48759264225 = 226036^2 + 220815^2
It is a 3-Lehmer number, since φ(99851537521) divides (99851537521-1)3.
It is a cyclic number.
It is not a de Polignac number, because 99851537521 - 231 = 97704053873 is a prime.
It is a deceptive number, since it divides R99851537520.
It is not an unprimeable number, because it can be changed into a prime (99851537581) 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, 1 + ... + 446881.
It is an arithmetic number, because the mean of its divisors is an integer number (24963051961).
It is a Poulet number, since it divides 299851537520-1.
Almost surely, 299851537521 is an apocalyptic number.
99851537521 is the 446881-st triangular number and also the 223441-st hexagonal number.
99851537521 is the 148961-st centered nonagonal number.
It is an amenable number.
99851537521 is a deficient number, since it is larger than the sum of its proper divisors (670323).
99851537521 is a wasteful number, since it uses less digits than its factorization.
99851537521 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 670322.
The product of its digits is 3402000, while the sum is 55.
The spelling of 99851537521 in words is "ninety-nine billion, eight hundred fifty-one million, five hundred thirty-seven thousand, five hundred twenty-one".