9921687989 has 8 divisors (see below), whose sum is σ = 9952228248. Its totient is φ = 9891187200.

The previous prime is 9921687983. The next prime is 9921687991. The reversal of 9921687989 is 9897861299.

It can be written as a sum of positive squares in 4 ways, for example, as 2584908964 + 7336779025 = 50842^2 + 85655^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9921687989 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 (9921687983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 539819 + ... + 557895.

It is an arithmetic number, because the mean of its divisors is an integer number (1244028531).

Almost surely, 2^9921687989 is an apocalyptic number.

It is an amenable number.

9921687989 is a deficient number, since it is larger than the sum of its proper divisors (30540259).

9921687989 is a wasteful number, since it uses less digits than its factorization.

9921687989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19735.

The product of its digits is 35271936, while the sum is 68.

The square root of 9921687989 is about 99607.6703321587. The cubic root of 9921687989 is about 2148.7960079932.

The spelling of 9921687989 in words is "nine billion, nine hundred twenty-one million, six hundred eighty-seven thousand, nine hundred eighty-nine".