1211984640 has 144 divisors (see below), whose sum is σ = 4300984800. Its totient is φ = 323186688.

The previous prime is 1211984593. The next prime is 1211984647. The reversal of 1211984640 is 464891121.

1211984640 is a `hidden beast` number, since 1 + 2 + 1 + 1 + 9 + 8 + 4 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1211984595 and 1211984604.

It is not an unprimeable number, because it can be changed into a prime (1211984647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17026 + ... + 52094.

It is an arithmetic number, because the mean of its divisors is an integer number (29867950).

Almost surely, 2^1211984640 is an apocalyptic number.

1211984640 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 1211984640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2150492400).

1211984640 is an abundant number, since it is smaller than the sum of its proper divisors (3089000160).

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

1211984640 is an equidigital number, since it uses as much as digits as its factorization.

1211984640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35099 (or 35079 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 1211984640 is about 34813.5697681235. The cubic root of 1211984640 is about 1066.1845182060.

The spelling of 1211984640 in words is "one billion, two hundred eleven million, nine hundred eighty-four thousand, six hundred forty".