74128633721 has 4 divisors (see below), whose sum is σ = 74129818212. Its totient is φ = 74127449232.

The previous prime is 74128633717. The next prime is 74128633753. The reversal of 74128633721 is 12733682147.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12733682147 = 271 ⋅46987757.

It can be written as a sum of positive squares in 2 ways, for example, as 4504423225 + 69624210496 = 67115^2 + 263864^2 .

It is a cyclic number.

It is not a de Polignac number, because 74128633721 - 2² = 74128633717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (74128633321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 492806 + ... + 625391.

It is an arithmetic number, because the mean of its divisors is an integer number (18532454553).

Almost surely, 2^74128633721 is an apocalyptic number.

It is an amenable number.

74128633721 is a deficient number, since it is larger than the sum of its proper divisors (1184491).

74128633721 is a wasteful number, since it uses less digits than its factorization.

74128633721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1184490.

The product of its digits is 338688, while the sum is 44.

The spelling of 74128633721 in words is "seventy-four billion, one hundred twenty-eight million, six hundred thirty-three thousand, seven hundred twenty-one".