1621321 has 4 divisors (see below), whose sum is σ = 1746052. Its totient is φ = 1496592.

The previous prime is 1621309. The next prime is 1621349. The reversal of 1621321 is 1231261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 881721 + 739600 = 939^2 + 860^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1621295 and 1621304.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621351) 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 3 ways as a sum of consecutive naturals, for example, 62346 + ... + 62371.

It is an arithmetic number, because the mean of its divisors is an integer number (436513).

2^1621321 is an apocalyptic number.

It is an amenable number.

1621321 is a deficient number, since it is larger than the sum of its proper divisors (124731).

1621321 is a wasteful number, since it uses less digits than its factorization.

1621321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124730.

The product of its digits is 72, while the sum is 16.

The square root of 1621321 is about 1273.3110381992. The cubic root of 1621321 is about 117.4779436493.

Adding to 1621321 its reverse (1231261), we get a palindrome (2852582).

The spelling of 1621321 in words is "one million, six hundred twenty-one thousand, three hundred twenty-one".