1221505056 has 96 divisors (see below), whose sum is σ = 3685651200. Its totient is φ = 393120000.

The previous prime is 1221505049. The next prime is 1221505067. The reversal of 1221505056 is 6505051221.

1221505056 is a `hidden beast` number, since 1 + 2 + 2 + 150 + 505 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

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 15 ways as a sum of consecutive naturals, for example, 681 + ... + 49431.

It is an arithmetic number, because the mean of its divisors is an integer number (38392200).

Almost surely, 2^1221505056 is an apocalyptic number.

1221505056 is a gapful number since it is divisible by the number (16) 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 1221505056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1842825600).

1221505056 is an abundant number, since it is smaller than the sum of its proper divisors (2464146144).

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

1221505056 is a wasteful number, since it uses less digits than its factorization.

1221505056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48799 (or 48785 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The square root of 1221505056 is about 34950.0365665045. The cubic root of 1221505056 is about 1068.9689476941.

Adding to 1221505056 its reverse (6505051221), we get a palindrome (7726556277).

The spelling of 1221505056 in words is "one billion, two hundred twenty-one million, five hundred five thousand, fifty-six".