37728721 has 4 divisors (see below), whose sum is σ = 37826100. Its totient is φ = 37631344.

The previous prime is 37728703. The next prime is 37728727. The reversal of 37728721 is 12782773.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12782773 = 967 ⋅13219.

It can be written as a sum of positive squares in 2 ways, for example, as 12327121 + 25401600 = 3511^2 + 5040^2 .

It is a cyclic number.

It is not a de Polignac number, because 37728721 - 2⁵ = 37728689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (37728727) 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, 48106 + ... + 48883.

It is an arithmetic number, because the mean of its divisors is an integer number (9456525).

Almost surely, 2^37728721 is an apocalyptic number.

It is an amenable number.

37728721 is a deficient number, since it is larger than the sum of its proper divisors (97379).

37728721 is an equidigital number, since it uses as much as digits as its factorization.

37728721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97378.

The product of its digits is 32928, while the sum is 37.

The square root of 37728721 is about 6142.3709591655. The cubic root of 37728721 is about 335.3956000777.

The spelling of 37728721 in words is "thirty-seven million, seven hundred twenty-eight thousand, seven hundred twenty-one".