3521721721 has 4 divisors (see below), whose sum is σ = 4024824832. Its totient is φ = 3018618612.

The previous prime is 3521721713. The next prime is 3521721743. The reversal of 3521721721 is 1271271253.

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.

It is a cyclic number.

It is not a de Polignac number, because 3521721721 - 2³ = 3521721713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3521721121) 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, 251551545 + ... + 251551558.

It is an arithmetic number, because the mean of its divisors is an integer number (1006206208).

Almost surely, 2^3521721721 is an apocalyptic number.

It is an amenable number.

3521721721 is a deficient number, since it is larger than the sum of its proper divisors (503103111).

3521721721 is an equidigital number, since it uses as much as digits as its factorization.

3521721721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503103110.

The product of its digits is 5880, while the sum is 31.

The square root of 3521721721 is about 59344.0959236890. The cubic root of 3521721721 is about 1521.4289599056.

Adding to 3521721721 its reverse (1271271253), we get a palindrome (4792992974).

The spelling of 3521721721 in words is "three billion, five hundred twenty-one million, seven hundred twenty-one thousand, seven hundred twenty-one".