8400000721 has 8 divisors (see below), whose sum is σ = 9634166784. Its totient is φ = 7174376160.

The previous prime is 8400000709. The next prime is 8400000727. The reversal of 8400000721 is 1270000048.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 8400000721 - 2⁵ = 8400000689 is a prime.

It is a super-2 number, since 2×8400000721² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 8400000692 and 8400000701.

It is not an unprimeable number, because it can be changed into a prime (8400000727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2133265 + ... + 2137198.

It is an arithmetic number, because the mean of its divisors is an integer number (1204270848).

Almost surely, 2^8400000721 is an apocalyptic number.

It is an amenable number.

8400000721 is a deficient number, since it is larger than the sum of its proper divisors (1234166063).

8400000721 is a wasteful number, since it uses less digits than its factorization.

8400000721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4270751.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 8400000721 is about 91651.5178324942. The cubic root of 8400000721 is about 2032.7927717902.

Adding to 8400000721 its reverse (1270000048), we get a palindrome (9670000769).

The spelling of 8400000721 in words is "eight billion, four hundred million, seven hundred twenty-one", and thus it is an aban number.