9981209421 has 16 divisors (see below), whose sum is σ = 15429889920. Its totient is φ = 6364828800.

The previous prime is 9981209393. The next prime is 9981209443. The reversal of 9981209421 is 1249021899.

It is not a de Polignac number, because 9981209421 - 2⁵ = 9981209389 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9981204421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8035780 + ... + 8037021.

It is an arithmetic number, because the mean of its divisors is an integer number (964368120).

Almost surely, 2^9981209421 is an apocalyptic number.

It is an amenable number.

9981209421 is a deficient number, since it is larger than the sum of its proper divisors (5448680499).

9981209421 is a wasteful number, since it uses less digits than its factorization.

9981209421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16072833 (or 16072827 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 45.

The square root of 9981209421 is about 99906.0029277520. The cubic root of 9981209421 is about 2153.0844080843.

The spelling of 9981209421 in words is "nine billion, nine hundred eighty-one million, two hundred nine thousand, four hundred twenty-one".