991983780 has 48 divisors (see below), whose sum is σ = 3086173440. Its totient is φ = 264528864.

The previous prime is 991983761. The next prime is 991983823. The reversal of 991983780 is 87389199.

It is a super-3 number, since 3×991983780³ (a number of 28 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 917964 + ... + 919043.

It is an arithmetic number, because the mean of its divisors is an integer number (64295280).

Almost surely, 2^991983780 is an apocalyptic number.

991983780 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

991983780 is an abundant number, since it is smaller than the sum of its proper divisors (2094189660).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991983780 is a wasteful number, since it uses less digits than its factorization.

991983780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1837025 (or 1837017 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The square root of 991983780 is about 31495.7740022372. The cubic root of 991983780 is about 997.3207547223.

The spelling of 991983780 in words is "nine hundred ninety-one million, nine hundred eighty-three thousand, seven hundred eighty".