74181721 has 2 divisors, whose sum is σ = 74181722. Its totient is φ = 74181720.

The previous prime is 74181691. The next prime is 74181743. The reversal of 74181721 is 12718147.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74149321 + 32400 = 8611^2 + 180^2 .

It is a cyclic number.

It is not a de Polignac number, because 74181721 - 2⁵ = 74181689 is a prime.

It is equal to p_4349182 and since 74181721 and 4349182 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (74181521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37090860 + 37090861.

It is an arithmetic number, because the mean of its divisors is an integer number (37090861).

Almost surely, 2^74181721 is an apocalyptic number.

It is an amenable number.

74181721 is a deficient number, since it is larger than the sum of its proper divisors (1).

74181721 is an equidigital number, since it uses as much as digits as its factorization.

74181721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3136, while the sum is 31.

The square root of 74181721 is about 8612.8811091295. The cubic root of 74181721 is about 420.1770247711.

Adding to 74181721 its reverse (12718147), we get a palindrome (86899868).

The spelling of 74181721 in words is "seventy-four million, one hundred eighty-one thousand, seven hundred twenty-one".