990921789 has 128 divisors (see below), whose sum is σ = 1888911360. Its totient is φ = 503884800.

The previous prime is 990921787. The next prime is 990921791. The reversal of 990921789 is 987129099.

It is an interprime number because it is at equal distance from previous prime (990921787) and next prime (990921791).

It is not a de Polignac number, because 990921789 - 2¹ = 990921787 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990921781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2034504 + ... + 2034990.

It is an arithmetic number, because the mean of its divisors is an integer number (14757120).

Almost surely, 2^990921789 is an apocalyptic number.

990921789 is a gapful number since it is divisible by the number (99) formed by its first and last digit.

It is an amenable number.

990921789 is a deficient number, since it is larger than the sum of its proper divisors (897989571).

990921789 is a wasteful number, since it uses less digits than its factorization.

990921789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 568 (or 562 counting only the distinct ones).

The product of its (nonzero) digits is 734832, while the sum is 54.

The square root of 990921789 is about 31478.9102257368. The cubic root of 990921789 is about 996.9647261002.

The spelling of 990921789 in words is "nine hundred ninety million, nine hundred twenty-one thousand, seven hundred eighty-nine".