72161010111721 has 2 divisors, whose sum is σ = 72161010111722. Its totient is φ = 72161010111720.

The previous prime is 72161010111583. The next prime is 72161010111731. The reversal of 72161010111721 is 12711101016127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64937085306025 + 7223924805696 = 8058355^2 + 2687736^2 .

It is a cyclic number.

It is not a de Polignac number, because 72161010111721 - 2⁹ = 72161010111209 is a prime.

It is a super-2 number, since 2×72161010111721² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (72161010111731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36080505055860 + 36080505055861.

It is an arithmetic number, because the mean of its divisors is an integer number (36080505055861).

Almost surely, 2^{72161010111721} is an apocalyptic number.

It is an amenable number.

72161010111721 is a deficient number, since it is larger than the sum of its proper divisors (1).

72161010111721 is an equidigital number, since it uses as much as digits as its factorization.

72161010111721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1176, while the sum is 31.

Adding to 72161010111721 its reverse (12711101016127), we get a palindrome (84872111127848).

The spelling of 72161010111721 in words is "seventy-two trillion, one hundred sixty-one billion, ten million, one hundred eleven thousand, seven hundred twenty-one".