5215156721 has 4 divisors (see below), whose sum is σ = 5215318500. Its totient is φ = 5214994944.

The previous prime is 5215156717. The next prime is 5215156747. The reversal of 5215156721 is 1276515125.

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 2016010000 + 3199146721 = 44900^2 + 56561^2 .

It is a cyclic number.

It is not a de Polignac number, because 5215156721 - 2² = 5215156717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (5215153721) 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, 14216 + ... + 103113.

It is an arithmetic number, because the mean of its divisors is an integer number (1303829625).

Almost surely, 2^5215156721 is an apocalyptic number.

It is an amenable number.

5215156721 is a deficient number, since it is larger than the sum of its proper divisors (161779).

5215156721 is a wasteful number, since it uses less digits than its factorization.

5215156721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161778.

The product of its digits is 21000, while the sum is 35.

The square root of 5215156721 is about 72216.0419920671. The cubic root of 5215156721 is about 1734.1598271927.

The spelling of 5215156721 in words is "five billion, two hundred fifteen million, one hundred fifty-six thousand, seven hundred twenty-one".