7647728921 has 8 divisors (see below), whose sum is σ = 8817609984. Its totient is φ = 6497184960.

The previous prime is 7647728917. The next prime is 7647728941. The reversal of 7647728921 is 1298277467.

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

It is not a de Polignac number, because 7647728921 - 2² = 7647728917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7647728941) 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, 4833425 + ... + 4835006.

It is an arithmetic number, because the mean of its divisors is an integer number (1102201248).

Almost surely, 2^7647728921 is an apocalyptic number.

It is an amenable number.

7647728921 is a deficient number, since it is larger than the sum of its proper divisors (1169881063).

7647728921 is a wasteful number, since it uses less digits than its factorization.

7647728921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9668551.

The product of its digits is 2370816, while the sum is 53.

The square root of 7647728921 is about 87451.2945644603. The cubic root of 7647728921 is about 1970.2023309927.

The spelling of 7647728921 in words is "seven billion, six hundred forty-seven million, seven hundred twenty-eight thousand, nine hundred twenty-one".