161721552116 has 6 divisors (see below), whose sum is σ = 283012716210. Its totient is φ = 80860776056.

The previous prime is 161721552073. The next prime is 161721552119. The reversal of 161721552116 is 611255127161.

It can be written as a sum of positive squares in only one way, i.e., 146271062116 + 15450490000 = 382454^2 + 124300^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 161721552116.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161721552119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20215194011 + ... + 20215194018.

It is an arithmetic number, because the mean of its divisors is an integer number (47168786035).

Almost surely, 2^161721552116 is an apocalyptic number.

It is an amenable number.

161721552116 is a deficient number, since it is larger than the sum of its proper divisors (121291164094).

161721552116 is a wasteful number, since it uses less digits than its factorization.

161721552116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40430388033 (or 40430388031 counting only the distinct ones).

The product of its digits is 25200, while the sum is 38.

Adding to 161721552116 its reverse (611255127161), we get a palindrome (772976679277).

The spelling of 161721552116 in words is "one hundred sixty-one billion, seven hundred twenty-one million, five hundred fifty-two thousand, one hundred sixteen".