1221612840 has 320 divisors, whose sum is σ = 4774872960. Its totient is φ = 274337280.

The previous prime is 1221612839. The next prime is 1221612871. The reversal of 1221612840 is 482161221.

1221612840 is a `hidden beast` number, since 1 + 2 + 2 + 1 + 612 + 8 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

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 79 ways as a sum of consecutive naturals, for example, 1383039 + ... + 1383921.

It is an arithmetic number, because the mean of its divisors is an integer number (14921478).

Almost surely, 2^1221612840 is an apocalyptic number.

1221612840 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 1221612840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2387436480).

1221612840 is an abundant number, since it is smaller than the sum of its proper divisors (3553260120).

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

1221612840 is a wasteful number, since it uses less digits than its factorization.

1221612840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 974 (or 961 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 1221612840 is about 34951.5785051262. The cubic root of 1221612840 is about 1069.0003882409. Note that the first 3 decimals are identical.

The spelling of 1221612840 in words is "one billion, two hundred twenty-one million, six hundred twelve thousand, eight hundred forty".