11981620 has 72 divisors (see below), whose sum is σ = 30506112. Its totient is φ = 3864960.

The previous prime is 11981603. The next prime is 11981623. The reversal of 11981620 is 2618911.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11981623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 196390 + ... + 196450.

It is an arithmetic number, because the mean of its divisors is an integer number (423696).

Almost surely, 2^11981620 is an apocalyptic number.

11981620 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 11981620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15253056).

11981620 is an abundant number, since it is smaller than the sum of its proper divisors (18524492).

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

11981620 is a wasteful number, since it uses less digits than its factorization.

11981620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161 (or 98 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 11981620 is about 3461.4476740231. The cubic root of 11981620 is about 228.8259007388.

The spelling of 11981620 in words is "eleven million, nine hundred eighty-one thousand, six hundred twenty".