161563431621 has 16 divisors (see below), whose sum is σ = 230859149184. Its totient is φ = 100241469504.

The previous prime is 161563431583. The next prime is 161563431703. The reversal of 161563431621 is 126134365161.

It is not a de Polignac number, because 161563431621 - 2¹³ = 161563423429 is a prime.

It is a super-2 number, since 2×161563431621² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161563431621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161563436621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31639326 + ... + 31644431.

It is an arithmetic number, because the mean of its divisors is an integer number (14428696824).

Almost surely, 2^161563431621 is an apocalyptic number.

It is an amenable number.

161563431621 is a deficient number, since it is larger than the sum of its proper divisors (69295717563).

161563431621 is a wasteful number, since it uses less digits than its factorization.

161563431621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63283820.

The product of its digits is 77760, while the sum is 39.

Adding to 161563431621 its reverse (126134365161), we get a palindrome (287697796782).

The spelling of 161563431621 in words is "one hundred sixty-one billion, five hundred sixty-three million, four hundred thirty-one thousand, six hundred twenty-one".