1981920 has 48 divisors (see below), whose sum is σ = 6244560. Its totient is φ = 528384.

The previous prime is 1981919. The next prime is 1981921. The reversal of 1981920 is 291891.

It is an interprime number because it is at equal distance from previous prime (1981919) and next prime (1981921).

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1585 + ... + 2544.

It is an arithmetic number, because the mean of its divisors is an integer number (130095).

2^1981920 is an apocalyptic number.

1981920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1981920 is an abundant number, since it is smaller than the sum of its proper divisors (4262640).

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

1981920 is a wasteful number, since it uses less digits than its factorization.

1981920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4147 (or 4139 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 1981920 is about 1407.8068049274. The cubic root of 1981920 is about 125.6112989686.

The spelling of 1981920 in words is "one million, nine hundred eighty-one thousand, nine hundred twenty".