1221101550 has 144 divisors (see below), whose sum is σ = 3423597840. Its totient is φ = 311646720.

The previous prime is 1221101549. The next prime is 1221101597. The reversal of 1221101550 is 551011221.

1221101550 is a `hidden beast` number, since 1 + 2 + 2 + 110 + 1 + 550 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1787509 + ... + 1788191.

It is an arithmetic number, because the mean of its divisors is an integer number (23774985).

Almost surely, 2^1221101550 is an apocalyptic number.

1221101550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221101550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1711798920).

1221101550 is an abundant number, since it is smaller than the sum of its proper divisors (2202496290).

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

1221101550 is a wasteful number, since it uses less digits than its factorization.

1221101550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 867 (or 859 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 18.

The square root of 1221101550 is about 34944.2634777155. The cubic root of 1221101550 is about 1068.8512287414.

Adding to 1221101550 its reverse (551011221), we get a palindrome (1772112771).

The spelling of 1221101550 in words is "one billion, two hundred twenty-one million, one hundred one thousand, five hundred fifty".