11561220 has 72 divisors (see below), whose sum is σ = 38263680. Its totient is φ = 2802240.

The previous prime is 11561219. The next prime is 11561237. The reversal of 11561220 is 2216511.

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

It is a junction number, because it is equal to n+sod(n) for n = 11561193 and 11561202.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 940 + ... + 4899.

It is an arithmetic number, because the mean of its divisors is an integer number (531440).

Almost surely, 2^11561220 is an apocalyptic number.

11561220 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 11561220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19131840).

11561220 is an abundant number, since it is smaller than the sum of its proper divisors (26702460).

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

11561220 is a wasteful number, since it uses less digits than its factorization.

11561220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5865 (or 5860 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 11561220 is about 3400.1794070313. The cubic root of 11561220 is about 226.1176978501.

Adding to 11561220 its reverse (2216511), we get a palindrome (13777731).

It can be divided in two parts, 11561 and 220, that added together give a triangular number (11781 = T₁₅₃).

The spelling of 11561220 in words is "eleven million, five hundred sixty-one thousand, two hundred twenty".