5209721721 has 24 divisors (see below), whose sum is σ = 7700284800. Its totient is φ = 3392607456.

The previous prime is 5209721719. The next prime is 5209721753. The reversal of 5209721721 is 1271279025.

5209721721 is a `hidden beast` number, since 520 + 97 + 21 + 7 + 21 = 666.

It is not a de Polignac number, because 5209721721 - 2¹ = 5209721719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (5209721221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 209455 + ... + 233003.

It is an arithmetic number, because the mean of its divisors is an integer number (320845200).

Almost surely, 2^5209721721 is an apocalyptic number.

It is an amenable number.

5209721721 is a deficient number, since it is larger than the sum of its proper divisors (2490563079).

5209721721 is a wasteful number, since it uses less digits than its factorization.

5209721721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24125 (or 24122 counting only the distinct ones).

The product of its (nonzero) digits is 17640, while the sum is 36.

The square root of 5209721721 is about 72178.4020396683. The cubic root of 5209721721 is about 1733.5571968712.

The spelling of 5209721721 in words is "five billion, two hundred nine million, seven hundred twenty-one thousand, seven hundred twenty-one".