1581720 has 96 divisors (see below), whose sum is σ = 5540400. Its totient is φ = 360192.

The previous prime is 1581719. The next prime is 1581721. The reversal of 1581720 is 271851.

It is an interprime number because it is at equal distance from previous prime (1581719) and next prime (1581721).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5746 + ... + 6014.

2^1581720 is an apocalyptic number.

1581720 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 1581720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2770200).

1581720 is an abundant number, since it is smaller than the sum of its proper divisors (3958680).

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

1581720 is a wasteful number, since it uses less digits than its factorization.

1581720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297 (or 286 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 1581720 is about 1257.6645021626. The cubic root of 1581720 is about 116.5135769818.

The spelling of 1581720 in words is "one million, five hundred eighty-one thousand, seven hundred twenty".