1621728 has 48 divisors (see below), whose sum is σ = 4732560. Its totient is φ = 540288.

The previous prime is 1621727. The next prime is 1621729. The reversal of 1621728 is 8271261.

It is an interprime number because it is at equal distance from previous prime (1621727) and next prime (1621729).

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 (27).

It is a nialpdrome in base 6.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75 + ... + 1802.

It is an arithmetic number, because the mean of its divisors is an integer number (98595).

2^1621728 is an apocalyptic number.

1621728 is a gapful number since it is divisible by the number (18) 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 1621728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2366280).

1621728 is an abundant number, since it is smaller than the sum of its proper divisors (3110832).

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

1621728 is a wasteful number, since it uses less digits than its factorization.

1621728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1896 (or 1882 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 1621728 is about 1273.4708477229. The cubic root of 1621728 is about 117.4877729845.

Adding to 1621728 its reverse (8271261), we get a palindrome (9892989).

It can be divided in two parts, 162 and 1728, that multiplied together give a 7-th power (279936 = 6⁷).

The spelling of 1621728 in words is "one million, six hundred twenty-one thousand, seven hundred twenty-eight".