9990561815 has 32 divisors (see below), whose sum is σ = 13235685120. Its totient is φ = 7193240064.

The previous prime is 9990561709. The next prime is 9990561829. The reversal of 9990561815 is 5181650999.

It is a cyclic number.

It is not a de Polignac number, because 9990561815 - 2¹² = 9990557719 is a prime.

It is a super-2 number, since 2×9990561815² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 815717 + ... + 827873.

It is an arithmetic number, because the mean of its divisors is an integer number (413615160).

Almost surely, 2^9990561815 is an apocalyptic number.

9990561815 is a deficient number, since it is larger than the sum of its proper divisors (3245123305).

9990561815 is a wasteful number, since it uses less digits than its factorization.

9990561815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12491.

The product of its (nonzero) digits is 874800, while the sum is 53.

The square root of 9990561815 is about 99952.7979348252. The cubic root of 9990561815 is about 2153.7566782413.

The spelling of 9990561815 in words is "nine billion, nine hundred ninety million, five hundred sixty-one thousand, eight hundred fifteen".