161004721 has 2 divisors, whose sum is σ = 161004722. Its totient is φ = 161004720.

The previous prime is 161004709. The next prime is 161004733. The reversal of 161004721 is 127400161.

161004721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (161004709) and next prime (161004733).

It can be written as a sum of positive squares in only one way, i.e., 157854096 + 3150625 = 12564^2 + 1775^2 .

It is a cyclic number.

It is not a de Polignac number, because 161004721 - 2²⁷ = 26786993 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 161004692 and 161004701.

It is not a weakly prime, because it can be changed into another prime (161005721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80502360 + 80502361.

It is an arithmetic number, because the mean of its divisors is an integer number (80502361).

Almost surely, 2^161004721 is an apocalyptic number.

It is an amenable number.

161004721 is a deficient number, since it is larger than the sum of its proper divisors (1).

161004721 is an equidigital number, since it uses as much as digits as its factorization.

161004721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 161004721 is about 12688.7635725472. The cubic root of 161004721 is about 544.0174998425.

Adding to 161004721 its reverse (127400161), we get a palindrome (288404882).

The spelling of 161004721 in words is "one hundred sixty-one million, four thousand, seven hundred twenty-one".