999981550 has 12 divisors (see below), whose sum is σ = 1859965776. Its totient is φ = 399992600.

The previous prime is 999981547. The next prime is 999981551. The reversal of 999981550 is 55189999.

It is a junction number, because it is equal to n+sod(n) for n = 999981491 and 999981500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999981551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9999766 + ... + 9999865.

It is an arithmetic number, because the mean of its divisors is an integer number (154997148).

Almost surely, 2^999981550 is an apocalyptic number.

999981550 is a deficient number, since it is larger than the sum of its proper divisors (859984226).

999981550 is a wasteful number, since it uses less digits than its factorization.

999981550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19999643 (or 19999638 counting only the distinct ones).

The product of its (nonzero) digits is 1312200, while the sum is 55.

The square root of 999981550 is about 31622.4848802241. The cubic root of 999981550 is about 999.9938499622.

The spelling of 999981550 in words is "nine hundred ninety-nine million, nine hundred eighty-one thousand, five hundred fifty".