8000403721 has 4 divisors (see below), whose sum is σ = 8000709444. Its totient is φ = 8000098000.

The previous prime is 8000403667. The next prime is 8000403727. The reversal of 8000403721 is 1273040008.

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 5526435600 + 2473968121 = 74340^2 + 49739^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8000403721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8000403727) 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, 109510 + ... + 167311.

It is an arithmetic number, because the mean of its divisors is an integer number (2000177361).

Almost surely, 2^8000403721 is an apocalyptic number.

It is an amenable number.

8000403721 is a deficient number, since it is larger than the sum of its proper divisors (305723).

8000403721 is a wasteful number, since it uses less digits than its factorization.

8000403721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305722.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 8000403721 is about 89444.9759405189. The cubic root of 8000403721 is about 2000.0336428507.

Adding to 8000403721 its reverse (1273040008), we get a palindrome (9273443729).

The spelling of 8000403721 in words is "eight billion, four hundred three thousand, seven hundred twenty-one".