163321621 has 4 divisors (see below), whose sum is σ = 163564972. Its totient is φ = 163078272.

The previous prime is 163321607. The next prime is 163321633. The reversal of 163321621 is 126123361.

163321621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 35880100 + 127441521 = 5990^2 + 11289^2 .

It is a cyclic number.

It is not a de Polignac number, because 163321621 - 2⁷ = 163321493 is a prime.

It is a super-3 number, since 3×163321621³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163321651) 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, 120666 + ... + 122011.

It is an arithmetic number, because the mean of its divisors is an integer number (40891243).

Almost surely, 2^163321621 is an apocalyptic number.

It is an amenable number.

163321621 is a deficient number, since it is larger than the sum of its proper divisors (243351).

163321621 is an equidigital number, since it uses as much as digits as its factorization.

163321621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243350.

The product of its digits is 1296, while the sum is 25.

The square root of 163321621 is about 12779.7347781556. The cubic root of 163321621 is about 546.6145997324.

Adding to 163321621 its reverse (126123361), we get a palindrome (289444982).

The spelling of 163321621 in words is "one hundred sixty-three million, three hundred twenty-one thousand, six hundred twenty-one".