1981656 has 48 divisors (see below), whose sum is σ = 5686200. Its totient is φ = 621312.

The previous prime is 1981649. The next prime is 1981663. The reversal of 1981656 is 6561891.

It is an interprime number because it is at equal distance from previous prime (1981649) and next prime (1981663).

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

It is a self number, because there is not a number n which added to its sum of digits gives 1981656.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 415 + ... + 2033.

2^1981656 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 1981656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2843100).

1981656 is an abundant number, since it is smaller than the sum of its proper divisors (3704544).

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

1981656 is a wasteful number, since it uses less digits than its factorization.

1981656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1648 (or 1641 counting only the distinct ones).

The product of its digits is 12960, while the sum is 36.

The square root of 1981656 is about 1407.7130389394. The cubic root of 1981656 is about 125.6057214049.

The spelling of 1981656 in words is "one million, nine hundred eighty-one thousand, six hundred fifty-six".