21545968801 has 12 divisors (see below), whose sum is σ = 25075442052. Its totient is φ = 18459305088.

The previous prime is 21545968799. The next prime is 21545968811. The reversal of 21545968801 is 10886954512.

It can be written as a sum of positive squares in 2 ways, for example, as 6656112225 + 14889856576 = 81585^2 + 122024^2 .

It is not a de Polignac number, because 21545968801 - 2¹ = 21545968799 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21545968811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3381 + ... + 207613.

It is an arithmetic number, because the mean of its divisors is an integer number (2089620171).

Almost surely, 2^21545968801 is an apocalyptic number.

It is an amenable number.

21545968801 is a deficient number, since it is larger than the sum of its proper divisors (3529473251).

21545968801 is a wasteful number, since it uses less digits than its factorization.

21545968801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206400 (or 206393 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 49.

The spelling of 21545968801 in words is "twenty-one billion, five hundred forty-five million, nine hundred sixty-eight thousand, eight hundred one".