9901636021 has 4 divisors (see below), whose sum is σ = 9905056812. Its totient is φ = 9898215232.

The previous prime is 9901635893. The next prime is 9901636027. The reversal of 9901636021 is 1206361099.

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 831168900 + 9070467121 = 28830^2 + 95239^2 .

It is a cyclic number.

It is not a de Polignac number, because 9901636021 - 2⁷ = 9901635893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9901636027) 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, 1706050 + ... + 1711843.

It is an arithmetic number, because the mean of its divisors is an integer number (2476264203).

Almost surely, 2^9901636021 is an apocalyptic number.

It is an amenable number.

9901636021 is a deficient number, since it is larger than the sum of its proper divisors (3420791).

9901636021 is a wasteful number, since it uses less digits than its factorization.

9901636021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3420790.

The product of its (nonzero) digits is 17496, while the sum is 37.

The square root of 9901636021 is about 99506.9646858952. The cubic root of 9901636021 is about 2147.3474423698.

The spelling of 9901636021 in words is "nine billion, nine hundred one million, six hundred thirty-six thousand, twenty-one".