1620646565 has 32 divisors (see below), whose sum is σ = 2057844096. Its totient is φ = 1223792640.

The previous prime is 1620646541. The next prime is 1620646603. The reversal of 1620646565 is 5656460261.

It is not a de Polignac number, because 1620646565 - 2¹⁴ = 1620630181 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 995282 + ... + 996908.

It is an arithmetic number, because the mean of its divisors is an integer number (64307628).

Almost surely, 2^1620646565 is an apocalyptic number.

It is an amenable number.

1620646565 is a deficient number, since it is larger than the sum of its proper divisors (437197531).

1620646565 is a wasteful number, since it uses less digits than its factorization.

1620646565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1829.

The product of its (nonzero) digits is 259200, while the sum is 41.

The square root of 1620646565 is about 40257.2548120211. The cubic root of 1620646565 is about 1174.6165194940.

The spelling of 1620646565 in words is "one billion, six hundred twenty million, six hundred forty-six thousand, five hundred sixty-five".