1221511104 has 280 divisors, whose sum is σ = 4083442176. Its totient is φ = 357696000.

The previous prime is 1221511099. The next prime is 1221511111. The reversal of 1221511104 is 4011151221.

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 39 ways as a sum of consecutive naturals, for example, 1767399 + ... + 1768089.

Almost surely, 2^1221511104 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221511104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2041721088).

1221511104 is an abundant number, since it is smaller than the sum of its proper divisors (2861931072).

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

1221511104 is a wasteful number, since it uses less digits than its factorization.

1221511104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 757 (or 738 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 1221511104 is about 34950.1230899120. The cubic root of 1221511104 is about 1068.9707119421.

Adding to 1221511104 its reverse (4011151221), we get a palindrome (5232662325).

The spelling of 1221511104 in words is "one billion, two hundred twenty-one million, five hundred eleven thousand, one hundred four".