1620509 has 4 divisors (see below), whose sum is σ = 1767840. Its totient is φ = 1473180.

The previous prime is 1620497. The next prime is 1620517. The reversal of 1620509 is 9050261.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1620509 - 2²⁰ = 571933 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 (1620539) 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, 73649 + ... + 73670.

It is an arithmetic number, because the mean of its divisors is an integer number (441960).

2^1620509 is an apocalyptic number.

It is an amenable number.

1620509 is a deficient number, since it is larger than the sum of its proper divisors (147331).

1620509 is a wasteful number, since it uses less digits than its factorization.

1620509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147330.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 1620509 is about 1272.9921445162. The cubic root of 1620509 is about 117.4583283645.

The spelling of 1620509 in words is "one million, six hundred twenty thousand, five hundred nine".