11987820 has 144 divisors (see below), whose sum is σ = 40360320. Its totient is φ = 2861568.

The previous prime is 11987783. The next prime is 11987837. The reversal of 11987820 is 2878911.

11987820 = T₄₀ + T₄₁ + ... + T₄₁₅.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 109926 + ... + 110034.

It is an arithmetic number, because the mean of its divisors is an integer number (280280).

Almost surely, 2^11987820 is an apocalyptic number.

11987820 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 11987820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20180160).

11987820 is an abundant number, since it is smaller than the sum of its proper divisors (28372500).

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

11987820 is a wasteful number, since it uses less digits than its factorization.

11987820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 11987820 is about 3462.3431372410. The cubic root of 11987820 is about 228.8653632918.

Adding to 11987820 its sum of digits (36), we get a triangular number (11987856 = T₄₈₉₆).

The spelling of 11987820 in words is "eleven million, nine hundred eighty-seven thousand, eight hundred twenty".