1620621 has 16 divisors (see below), whose sum is σ = 2421120. Its totient is φ = 1071360.

The previous prime is 1620617. The next prime is 1620629. The reversal of 1620621 is 1260261.

It is a happy number.

It is not a de Polignac number, because 1620621 - 2² = 1620617 is a prime.

1620621 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1620594 and 1620603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620629) 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 15 ways as a sum of consecutive naturals, for example, 5056 + ... + 5366.

It is an arithmetic number, because the mean of its divisors is an integer number (151320).

2^1620621 is an apocalyptic number.

It is an amenable number.

1620621 is a deficient number, since it is larger than the sum of its proper divisors (800499).

1620621 is a wasteful number, since it uses less digits than its factorization.

1620621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 513 (or 507 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1620621 is about 1273.0361346011. The cubic root of 1620621 is about 117.4610343105.

Adding to 1620621 its reverse (1260261), we get a palindrome (2880882).

The spelling of 1620621 in words is "one million, six hundred twenty thousand, six hundred twenty-one".