1981520 has 80 divisors (see below), whose sum is σ = 5142528. Its totient is φ = 706560.

The previous prime is 1981517. The next prime is 1981523. The reversal of 1981520 is 251891.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1981517) and next prime (1981523).

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 1981520.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981523) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42137 + ... + 42183.

2^1981520 is an apocalyptic number.

1981520 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 1981520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2571264).

1981520 is an abundant number, since it is smaller than the sum of its proper divisors (3161008).

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

1981520 is a wasteful number, since it uses less digits than its factorization.

1981520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108 (or 102 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 1981520 is about 1407.6647328110. The cubic root of 1981520 is about 125.6028479211.

The spelling of 1981520 in words is "one million, nine hundred eighty-one thousand, five hundred twenty".