161026721 has 8 divisors (see below), whose sum is σ = 166811400. Its totient is φ = 155330560.

The previous prime is 161026709. The next prime is 161026757. The reversal of 161026721 is 127620161.

It can be written as a sum of positive squares in 4 ways, for example, as 27300625 + 133726096 = 5225^2 + 11564^2 .

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 161026721 - 2¹⁸ = 160764577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161020721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18416 + ... + 25713.

It is an arithmetic number, because the mean of its divisors is an integer number (20851425).

Almost surely, 2^161026721 is an apocalyptic number.

It is an amenable number.

161026721 is a deficient number, since it is larger than the sum of its proper divisors (5784679).

161026721 is an equidigital number, since it uses as much as digits as its factorization.

161026721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44259.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 161026721 is about 12689.6304516719. The cubic root of 161026721 is about 544.0422772524.

Adding to 161026721 its reverse (127620161), we get a palindrome (288646882).

The spelling of 161026721 in words is "one hundred sixty-one million, twenty-six thousand, seven hundred twenty-one".