21556406041 has 9 divisors (see below), whose sum is σ = 22101167389. Its totient is φ = 21024767200.

The previous prime is 21556406029. The next prime is 21556406051. The reversal of 21556406041 is 14060465512.

The square root of 21556406041 is 146821.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 281266441 + 21275139600 = 16771^2 + 145860^2 .

It is not a de Polignac number, because 21556406041 - 2²⁹ = 21019535129 is a prime.

It is a super-2 number, since 2×21556406041² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21556405988 and 21556406006.

It is not an unprimeable number, because it can be changed into a prime (21556406051) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 6017871 + ... + 6021451.

Almost surely, 2^21556406041 is an apocalyptic number.

21556406041 is the 146821-st square number.

21556406041 is the 73411-st centered octagonal number.

It is an amenable number.

21556406041 is a deficient number, since it is larger than the sum of its proper divisors (544761348).

21556406041 is an frugal number, since it uses more digits than its factorization.

21556406041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7244 (or 3622 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 34.

The spelling of 21556406041 in words is "twenty-one billion, five hundred fifty-six million, four hundred six thousand, forty-one".