74721721 has 4 divisors (see below), whose sum is σ = 76544244. Its totient is φ = 72899200.

The previous prime is 74721701. The next prime is 74721727. The reversal of 74721721 is 12712747.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 39200121 + 35521600 = 6261^2 + 5960^2 .

It is a cyclic number.

It is not a de Polignac number, because 74721721 - 2⁹ = 74721209 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (74721727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 911200 + ... + 911281.

It is an arithmetic number, because the mean of its divisors is an integer number (19136061).

Almost surely, 2^74721721 is an apocalyptic number.

It is an amenable number.

74721721 is a deficient number, since it is larger than the sum of its proper divisors (1822523).

74721721 is a wasteful number, since it uses less digits than its factorization.

74721721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1822522.

The product of its digits is 5488, while the sum is 31.

The square root of 74721721 is about 8644.1726613945. The cubic root of 74721721 is about 421.1941093479.

The spelling of 74721721 in words is "seventy-four million, seven hundred twenty-one thousand, seven hundred twenty-one".