3678721 has 4 divisors (see below), whose sum is σ = 3685444. Its totient is φ = 3672000.

The previous prime is 3678713. The next prime is 3678743. The reversal of 3678721 is 1278763.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1278763 = 127 ⋅10069.

It can be written as a sum of positive squares in 2 ways, for example, as 1718721 + 1960000 = 1311^2 + 1400^2 .

It is a cyclic number.

It is not a de Polignac number, because 3678721 - 2³ = 3678713 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3678751) 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, 2460 + ... + 3661.

It is an arithmetic number, because the mean of its divisors is an integer number (921361).

Almost surely, 2^3678721 is an apocalyptic number.

It is an amenable number.

3678721 is a deficient number, since it is larger than the sum of its proper divisors (6723).

3678721 is an equidigital number, since it uses as much as digits as its factorization.

3678721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6722.

The product of its digits is 14112, while the sum is 34.

The square root of 3678721 is about 1917.9992179352. Note that the first 3 decimals coincide. The cubic root of 3678721 is about 154.3709643424.

The spelling of 3678721 in words is "three million, six hundred seventy-eight thousand, seven hundred twenty-one".