7155712721 has 4 divisors (see below), whose sum is σ = 7532329200. Its totient is φ = 6779096244.

The previous prime is 7155712703. The next prime is 7155712747. The reversal of 7155712721 is 1272175517.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1272175517 = 23 ⋅55311979.

It is a cyclic number.

It is not a de Polignac number, because 7155712721 - 2¹⁴ = 7155696337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7155712121) 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, 188308211 + ... + 188308248.

It is an arithmetic number, because the mean of its divisors is an integer number (1883082300).

Almost surely, 2^7155712721 is an apocalyptic number.

It is an amenable number.

7155712721 is a deficient number, since it is larger than the sum of its proper divisors (376616479).

7155712721 is a wasteful number, since it uses less digits than its factorization.

7155712721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 376616478.

The product of its digits is 34300, while the sum is 38.

The square root of 7155712721 is about 84591.4459091462. The cubic root of 7155712721 is about 1927.0114665520.

The spelling of 7155712721 in words is "seven billion, one hundred fifty-five million, seven hundred twelve thousand, seven hundred twenty-one".