161633621 has 4 divisors (see below), whose sum is σ = 161752044. Its totient is φ = 161515200.

The previous prime is 161633609. The next prime is 161633629. The reversal of 161633621 is 126336161.

It is a happy number.

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 82174225 + 79459396 = 9065^2 + 8914^2 .

It is a cyclic number.

It is not a de Polignac number, because 161633621 - 2⁶ = 161633557 is a prime.

It is a super-2 number, since 2×161633621² = 52250854875143282, which contains 22 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 (161633629) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 57140 + ... + 59901.

It is an arithmetic number, because the mean of its divisors is an integer number (40438011).

Almost surely, 2^161633621 is an apocalyptic number.

It is an amenable number.

161633621 is a deficient number, since it is larger than the sum of its proper divisors (118423).

161633621 is a wasteful number, since it uses less digits than its factorization.

161633621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118422.

The product of its digits is 3888, while the sum is 29.

The square root of 161633621 is about 12713.5211880895. The cubic root of 161633621 is about 544.7249078822.

Adding to 161633621 its reverse (126336161), we get a palindrome (287969782).

The spelling of 161633621 in words is "one hundred sixty-one million, six hundred thirty-three thousand, six hundred twenty-one".