1621612165 has 4 divisors (see below), whose sum is σ = 1945934604. Its totient is φ = 1297289728.

The previous prime is 1621612163. The next prime is 1621612211. The reversal of 1621612165 is 5612161261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 973502401 + 648109764 = 31201^2 + 25458^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621612165 - 2¹ = 1621612163 is a prime.

It is a super-3 number, since 3×1621612165³ (a number of 29 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621612163) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 162161212 + ... + 162161221.

It is an arithmetic number, because the mean of its divisors is an integer number (486483651).

Almost surely, 2^1621612165 is an apocalyptic number.

It is an amenable number.

1621612165 is a deficient number, since it is larger than the sum of its proper divisors (324322439).

1621612165 is an equidigital number, since it uses as much as digits as its factorization.

1621612165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324322438.

The product of its digits is 4320, while the sum is 31.

The square root of 1621612165 is about 40269.2458955963. The cubic root of 1621612165 is about 1174.8497565555.

The spelling of 1621612165 in words is "one billion, six hundred twenty-one million, six hundred twelve thousand, one hundred sixty-five".