161471721 has 16 divisors (see below), whose sum is σ = 218289600. Its totient is φ = 106157568.

The previous prime is 161471711. The next prime is 161471749. The reversal of 161471721 is 127174161.

It is not a de Polignac number, because 161471721 - 2⁶ = 161471657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161471711) 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, 164785 + ... + 165761.

It is an arithmetic number, because the mean of its divisors is an integer number (13643100).

Almost surely, 2^161471721 is an apocalyptic number.

It is an amenable number.

161471721 is a deficient number, since it is larger than the sum of its proper divisors (56817879).

161471721 is an equidigital number, since it uses as much as digits as its factorization.

161471721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1688.

The product of its digits is 2352, while the sum is 30.

The square root of 161471721 is about 12707.1523560552. The cubic root of 161471721 is about 544.5429729112.

The spelling of 161471721 in words is "one hundred sixty-one million, four hundred seventy-one thousand, seven hundred twenty-one".