5561220721 has 16 divisors (see below), whose sum is σ = 6479424000. Its totient is φ = 4674765888.

The previous prime is 5561220683. The next prime is 5561220779. The reversal of 5561220721 is 1270221655.

It is a cyclic number.

It is not a de Polignac number, because 5561220721 - 2¹³ = 5561212529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (5561220121) 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, 48651 + ... + 116143.

It is an arithmetic number, because the mean of its divisors is an integer number (404964000).

Almost surely, 2^5561220721 is an apocalyptic number.

It is an amenable number.

5561220721 is a deficient number, since it is larger than the sum of its proper divisors (918203279).

5561220721 is a wasteful number, since it uses less digits than its factorization.

5561220721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67728.

The product of its (nonzero) digits is 8400, while the sum is 31.

The square root of 5561220721 is about 74573.5926518228. The cubic root of 5561220721 is about 1771.6994244503.

The spelling of 5561220721 in words is "five billion, five hundred sixty-one million, two hundred twenty thousand, seven hundred twenty-one".