5521621721 has 16 divisors (see below), whose sum is σ = 7121485440. Its totient is φ = 4154196480.

The previous prime is 5521621691. The next prime is 5521621723. The reversal of 5521621721 is 1271261255.

It is not a de Polignac number, because 5521621721 - 2¹⁴ = 5521605337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (5521621723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1234136 + ... + 1238601.

It is an arithmetic number, because the mean of its divisors is an integer number (445092840).

Almost surely, 2^5521621721 is an apocalyptic number.

It is an amenable number.

5521621721 is a deficient number, since it is larger than the sum of its proper divisors (1599863719).

5521621721 is a wasteful number, since it uses less digits than its factorization.

5521621721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2472784.

The product of its digits is 8400, while the sum is 32.

The square root of 5521621721 is about 74307.6154980094. The cubic root of 5521621721 is about 1767.4842403401.

Adding to 5521621721 its reverse (1271261255), we get a palindrome (6792882976).

The spelling of 5521621721 in words is "five billion, five hundred twenty-one million, six hundred twenty-one thousand, seven hundred twenty-one".