161630840721 has 16 divisors (see below), whose sum is σ = 260782533504. Its totient is φ = 86927510784.

The previous prime is 161630840713. The next prime is 161630840771. The reversal of 161630840721 is 127048036161.

It is not a de Polignac number, because 161630840721 - 2³ = 161630840713 is a prime.

It is a super-2 number, since 2×161630840721² (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 161630840721.

It is not an unprimeable number, because it can be changed into a prime (161630840771) 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, 226373370 + ... + 226374083.

It is an arithmetic number, because the mean of its divisors is an integer number (16298908344).

Almost surely, 2^161630840721 is an apocalyptic number.

It is an amenable number.

161630840721 is a deficient number, since it is larger than the sum of its proper divisors (99151692783).

161630840721 is a wasteful number, since it uses less digits than its factorization.

161630840721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 452747480.

The product of its (nonzero) digits is 48384, while the sum is 39.

Adding to 161630840721 its reverse (127048036161), we get a palindrome (288678876882).

The spelling of 161630840721 in words is "one hundred sixty-one billion, six hundred thirty million, eight hundred forty thousand, seven hundred twenty-one".