1917121980 has 24 divisors (see below), whose sum is σ = 5367941712. Its totient is φ = 511232512.

The previous prime is 1917121957. The next prime is 1917121981. The reversal of 1917121980 is 891217191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1917121981) 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 7 ways as a sum of consecutive naturals, for example, 15975957 + ... + 15976076.

It is an arithmetic number, because the mean of its divisors is an integer number (223664238).

Almost surely, 2^1917121980 is an apocalyptic number.

1917121980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1917121980 is an abundant number, since it is smaller than the sum of its proper divisors (3450819732).

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

1917121980 is a wasteful number, since it uses less digits than its factorization.

1917121980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31952045 (or 31952043 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 39.

The square root of 1917121980 is about 43784.9515244679. The cubic root of 1917121980 is about 1242.2716725700.

The spelling of 1917121980 in words is "one billion, nine hundred seventeen million, one hundred twenty-one thousand, nine hundred eighty".