1620705 has 16 divisors (see below), whose sum is σ = 2620800. Its totient is φ = 855168.

The previous prime is 1620679. The next prime is 1620733. The reversal of 1620705 is 5070261.

It is not a de Polignac number, because 1620705 - 2⁸ = 1620449 is a prime.

It is an Ulam number.

1620705 is a lucky number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1021 + ... + 2069.

It is an arithmetic number, because the mean of its divisors is an integer number (163800).

2^1620705 is an apocalyptic number.

1620705 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1620705 is a deficient number, since it is larger than the sum of its proper divisors (1000095).

1620705 is a wasteful number, since it uses less digits than its factorization.

1620705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1160.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 1620705 is about 1273.0691261672. The cubic root of 1620705 is about 117.4630636883.

Adding to 1620705 its reverse (5070261), we get a palindrome (6690966).

The spelling of 1620705 in words is "one million, six hundred twenty thousand, seven hundred five".