1621789 has 4 divisors (see below), whose sum is σ = 1746556. Its totient is φ = 1497024.

The previous prime is 1621771. The next prime is 1621793. The reversal of 1621789 is 9871261.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9871261 = 137 ⋅72053.

It can be written as a sum of positive squares in 2 ways, for example, as 1071225 + 550564 = 1035^2 + 742^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621789 - 2¹¹ = 1619741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62364 + ... + 62389.

It is an arithmetic number, because the mean of its divisors is an integer number (436639).

2^1621789 is an apocalyptic number.

It is an amenable number.

1621789 is a deficient number, since it is larger than the sum of its proper divisors (124767).

1621789 is a wasteful number, since it uses less digits than its factorization.

1621789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124766.

The product of its digits is 6048, while the sum is 34.

The square root of 1621789 is about 1273.4947977907. The cubic root of 1621789 is about 117.4892460356.

The spelling of 1621789 in words is "one million, six hundred twenty-one thousand, seven hundred eighty-nine".