1218961920 has 320 divisors, whose sum is σ = 4355721216. Its totient is φ = 288276480.

The previous prime is 1218961907. The next prime is 1218961921. The reversal of 1218961920 is 291698121.

It is a tau number, because it is divible by the number of its divisors (320).

It is not an unprimeable number, because it can be changed into a prime (1218961921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3970407 + ... + 3970713.

Almost surely, 2^1218961920 is an apocalyptic number.

1218961920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1218961920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2177860608).

1218961920 is an abundant number, since it is smaller than the sum of its proper divisors (3136759296).

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

1218961920 is a wasteful number, since it uses less digits than its factorization.

1218961920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 375 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 39.

The square root of 1218961920 is about 34913.6351587743. The cubic root of 1218961920 is about 1068.2265787562.

The spelling of 1218961920 in words is "one billion, two hundred eighteen million, nine hundred sixty-one thousand, nine hundred twenty".