162721721 has 2 divisors, whose sum is σ = 162721722. Its totient is φ = 162721720.

The previous prime is 162721687. The next prime is 162721729. The reversal of 162721721 is 127127261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147355321 + 15366400 = 12139^2 + 3920^2 .

It is a cyclic number.

It is not a de Polignac number, because 162721721 - 2¹⁰ = 162720697 is a prime.

It is not a weakly prime, because it can be changed into another prime (162721729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81360860 + 81360861.

It is an arithmetic number, because the mean of its divisors is an integer number (81360861).

Almost surely, 2^162721721 is an apocalyptic number.

It is an amenable number.

162721721 is a deficient number, since it is larger than the sum of its proper divisors (1).

162721721 is an equidigital number, since it uses as much as digits as its factorization.

162721721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2352, while the sum is 29.

The square root of 162721721 is about 12756.2424326288. The cubic root of 162721721 is about 545.9445181943.

Adding to 162721721 its reverse (127127261), we get a palindrome (289848982).

The spelling of 162721721 in words is "one hundred sixty-two million, seven hundred twenty-one thousand, seven hundred twenty-one".