991984421 has 4 divisors (see below), whose sum is σ = 992314092. Its totient is φ = 991654752.

The previous prime is 991984387. The next prime is 991984429. The reversal of 991984421 is 124489199.

991984421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 821968900 + 170015521 = 28670^2 + 13039^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991984421 is a prime.

It is a super-3 number, since 3×991984421³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991984429) 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, 160280 + ... + 166353.

It is an arithmetic number, because the mean of its divisors is an integer number (248078523).

Almost surely, 2^991984421 is an apocalyptic number.

It is an amenable number.

991984421 is a deficient number, since it is larger than the sum of its proper divisors (329671).

991984421 is a wasteful number, since it uses less digits than its factorization.

991984421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329670.

The product of its digits is 186624, while the sum is 47.

The square root of 991984421 is about 31495.7841782039. The cubic root of 991984421 is about 997.3209695384.

The spelling of 991984421 in words is "nine hundred ninety-one million, nine hundred eighty-four thousand, four hundred twenty-one".