161631447721 has 8 divisors (see below), whose sum is σ = 164786275584. Its totient is φ = 158480515440.

The previous prime is 161631447701. The next prime is 161631447751. The reversal of 161631447721 is 127744136161.

It is a happy number.

161631447721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161631447721 - 2¹¹ = 161631445673 is a prime.

It is a super-2 number, since 2×161631447721² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161631447701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 890035 + ... + 1056136.

It is an arithmetic number, because the mean of its divisors is an integer number (20598284448).

Almost surely, 2^161631447721 is an apocalyptic number.

It is an amenable number.

161631447721 is a deficient number, since it is larger than the sum of its proper divisors (3154827863).

161631447721 is a wasteful number, since it uses less digits than its factorization.

161631447721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1947791.

The product of its digits is 169344, while the sum is 43.

The spelling of 161631447721 in words is "one hundred sixty-one billion, six hundred thirty-one million, four hundred forty-seven thousand, seven hundred twenty-one".